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Molnár H, Marosi C, Becske M, Békési E, Farkas K, Stefanics G, Czigler I, Csukly G. A comparison of visual and acoustic mismatch negativity as potential biomarkers in schizophrenia. Sci Rep 2024; 14:992. [PMID: 38200103 PMCID: PMC10782025 DOI: 10.1038/s41598-023-49983-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Accepted: 12/14/2023] [Indexed: 01/12/2024] Open
Abstract
Mismatch negativity (MMN) is an event-related potential (ERP) component generated when an unexpected deviant stimulus occurs in a pattern of standard stimuli. Several studies showed that the MMN response to both auditory and visual stimuli is attenuated in schizophrenia. While previous studies investigated auditory and visual MMN in different cohorts, here we examined the potential clinical utility of MMN responses to auditory and visual stimuli within the same group of patients. Altogether 39 patients with schizophrenia and 39 healthy controls matched in age, gender, and education were enrolled. We recorded EEG using 64 channels in eight experimental blocks where we presented auditory and visual stimulus sequences. Mismatch responses were obtained by subtracting responses to standard from the physically identical deviant stimuli. We found a significant MMN response to the acoustic stimuli in the control group, whereas no significant mismatch response was observed in the patient group. The group difference was significant for the acoustic stimuli. The 12 vane windmill pattern evoked a significant MMN response in the early time window in the control group but not in the patient group. The 6 vane windmill pattern evoked MMN only in the patient group. However, we found no significant difference between the groups. Furthermore, we found no correlation between the clinical variables and the MMN amplitudes. Our results suggest that predictive processes underlying mismatch generation in patients with schizophrenia may be more affected in the acoustic compared to the visual domain. Acoustic MMN tends to be a more promising biomarker in schizophrenia.
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Affiliation(s)
- Hajnalka Molnár
- Department of Psychiatry and Psychotherapy, Semmelweis University, Budapest, Hungary
| | - Csilla Marosi
- Department of Psychiatry and Psychotherapy, Semmelweis University, Budapest, Hungary
| | - Melinda Becske
- Department of Psychiatry and Psychotherapy, Semmelweis University, Budapest, Hungary
| | - Emese Békési
- Department of Psychiatry and Psychotherapy, Semmelweis University, Budapest, Hungary
| | - Kinga Farkas
- Department of Psychiatry and Psychotherapy, Semmelweis University, Budapest, Hungary
| | - Gábor Stefanics
- Department of Psychiatry and Psychotherapy, Semmelweis University, Budapest, Hungary
| | - István Czigler
- Institute of Cognitive Neuroscience and Psychology, RCNS, HU-RES, Budapest, Hungary
| | - Gábor Csukly
- Department of Psychiatry and Psychotherapy, Semmelweis University, Budapest, Hungary.
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2
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Miller CL. The Epigenetics of Psychosis: A Structured Review with Representative Loci. Biomedicines 2022; 10:biomedicines10030561. [PMID: 35327363 PMCID: PMC8945330 DOI: 10.3390/biomedicines10030561] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 02/24/2022] [Accepted: 02/26/2022] [Indexed: 02/04/2023] Open
Abstract
The evidence for an environmental component in chronic psychotic disorders is strong and research on the epigenetic manifestations of these environmental impacts has commenced in earnest. In reviewing this research, the focus is on three genes as models for differential methylation, MCHR1, AKT1 and TDO2, each of which have been investigated for genetic association with psychotic disorders. Environmental factors associated with psychotic disorders, and which interact with these model genes, are explored in depth. The location of transcription factor motifs relative to key methylation sites is evaluated for predicted gene expression results, and for other sites, evidence is presented for methylation directing alternative splicing. Experimental results from key studies show differential methylation: for MCHR1, in psychosis cases versus controls; for AKT1, as a pre-existing methylation pattern influencing brain activation following acute administration of a psychosis-eliciting environmental stimulus; and for TDO2, in a pattern associated with a developmental factor of risk for psychosis, in all cases the predicted expression impact being highly dependent on location. Methylation induced by smoking, a confounding variable, exhibits an intriguing pattern for all three genes. Finally, how differential methylation meshes with Darwinian principles is examined, in particular as it relates to the “flexible stem” theory of evolution.
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3
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Notarangelo FM, Schwarcz R. A single prenatal lipopolysaccharide injection has acute, but not long-lasting, effects on cerebral kynurenine pathway metabolism in mice. Eur J Neurosci 2021; 54:5968-5981. [PMID: 34363411 DOI: 10.1111/ejn.15416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 07/26/2021] [Accepted: 08/03/2021] [Indexed: 11/28/2022]
Abstract
In rodents, a single injection of lipopolysaccharide (LPS) during gestation causes chemical and functional abnormalities in the offspring. These effects may involve changes in the kynurenine pathway (KP) of tryptophan degradation and may provide insights into the pathophysiology of psychiatric diseases. Using CD1 mice, we examined acute and long-term effects of prenatal LPS treatment on the levels of kynurenine and its neuroactive downstream products kynurenic acid (KYNA), 3-hydroxykynurenine (3-HK) and quinolinic acid. To this end, LPS (100 μg/kg, i.p.) was administered on gestational day 15, and KP metabolites were measured 4 and 24 h later or in adulthood. After 4 h, kynurenine, KYNA and 3-HK levels were elevated in the fetal brain, 3-HK and KYNA levels were increased in the maternal plasma, and kynurenine was increased in the maternal brain, whereas no changes were seen in the placenta. These effects were less prominent after 24 h, and prenatal LPS did not affect the basal levels of KP metabolites in the forebrain of adult animals. In addition, a second LPS injection (1 mg/kg) in adulthood in the offspring of prenatally saline- and LPS-treated mice caused a similar elevation in 3-HK levels in both groups after 24 h, but the effect was significantly more pronounced in male mice. Thus, acute immune activation during pregnancy has only short-lasting effects on KP metabolism and does not cause cerebral KP metabolites to be disproportionally affected by a second immune challenge in adulthood. However, prenatal KYNA elevations still contribute to functional abnormalities in the offspring.
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Affiliation(s)
- Francesca M Notarangelo
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Robert Schwarcz
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, Maryland, USA
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4
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Dimitriadis SI. Reconfiguration of αmplitude driven dominant coupling modes (DoCM) mediated by α-band in adolescents with schizophrenia spectrum disorders. Prog Neuropsychopharmacol Biol Psychiatry 2021; 108:110073. [PMID: 32805332 DOI: 10.1016/j.pnpbp.2020.110073] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 08/10/2020] [Accepted: 08/10/2020] [Indexed: 12/16/2022]
Abstract
Electroencephalography (EEG) based biomarkers have been shown to correlate with the presence of psychotic disorders. Increased delta and decreased alpha power in psychosis indicate an abnormal arousal state. We investigated brain activity across the basic EEG frequencies and also dynamic functional connectivity of both intra and cross-frequency coupling that could reveal a neurophysiological biomarker linked to an aberrant modulating role of alpha frequency in adolescents with schizophrenia spectrum disorders (SSDs). A dynamic functional connectivity graph (DFCG) has been estimated using the imaginary part of phase lag value (iPLV) and correlation of the envelope (corrEnv). We analyzed DFCG profiles of electroencephalographic resting state (eyes closed) recordings of healthy controls (HC) (n = 39) and SSDs subjects (n = 45) in basic frequency bands {δ,θ,α1,α2,β1,β2,γ}. In our analysis, we incorporated both intra and cross-frequency coupling modes. Adopting our recent Dominant Coupling Mode (DοCM) model leads to the construction of an integrated DFCG (iDFCG) that encapsulates the functional strength and the DοCM of every pair of brain areas. We revealed significantly higher ratios of delta/alpha1,2 power spectrum in SSDs subjects versus HC. The probability distribution (PD) of amplitude driven DoCM mediated by alpha frequency differentiated SSDs from HC with absolute accuracy (100%). The network Flexibility Index (FI) was significantly lower for subjects with SSDs compared to the HC group. Our analysis supports the central role of alpha frequency alterations in the neurophysiological mechanisms of SSDs. Currents findings open up new diagnostic pathways to clinical detection of SSDs and support the design of rational neurofeedback training.
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Affiliation(s)
- Stavros I Dimitriadis
- Cardiff University Brain Research Imaging Centre (CUBRIC), School of Psychology, College of Biomedical and Life Sciences, Cardiff University, Cardiff, United Kingdom; Neuroinformatics Group, Cardiff University Brain Research Imaging Centre (CUBRIC), School of Psychology, College of Biomedical and Life Sciences, Cardiff University, Cardiff, United Kingdom; Division of Psychological Medicine and Clinical Neurosciences, School of Medicine, College of Biomedical and Life Sciences, Cardiff University, Cardiff, United Kingdom; School of Psychology, College of Biomedical and Life Sciences,Cardiff University, Cardiff, United Kingdom; Neuroscience and Mental Health Research Institute, School of Medicine, College of Biomedical and Life Sciences,Cardiff University, Cardiff, United Kingdom; MRC Centre for Neuropsychiatric Genetics and Genomics, School of Medicine, College of Biomedical and Life Sciences, Cardiff University, Cardiff, United Kingdom.
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5
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Profile of the Nicotinic Cholinergic Receptor Alpha 7 Subunit Gene Expression is Associated with Response to Varenicline Treatment. Genes (Basel) 2020; 11:genes11070746. [PMID: 32640505 PMCID: PMC7397196 DOI: 10.3390/genes11070746] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 06/15/2020] [Accepted: 06/25/2020] [Indexed: 12/11/2022] Open
Abstract
INTRODUCTION Smoking is considered the leading cause of preventable morbidity and mortality worldwide. Studies have sought to identify predictors of response to smoking cessation treatments. The aim of this study was to analyze a possible association of target gene expression for smoking cessation with varenicline. METHODS We included 74 smokers starting treatment with varenicline. Gene expression analysis was performed through the custom RT² Profiler qPCR array assay, including 17 genes. Times for sample collection were before the start of therapy (T0) and two weeks (T2) and four weeks (T4) after the start of treatment. RESULTS For gene expression analysis, we selected 14 patients who had success and 13 patients resistant to varenicline treatment. Success was considered to be when a patient achieved tobacco abstinence until the fourth week of treatment and resistant was when a patient had not stopped smoking as of the fourth week of treatment. We observed a significant difference for CHRNA7 gene expression: in the resistant group, samples from T2 and T4 had lower expression compared with T0 (fold change: 0.38, P = 0.007; fold change: 0.67, P = 0.004; respectively). CONCLUSION This exploratory clinical study, searching for a possible predictor of effectiveness for varenicline, reaffirmed the association of the α7 nAChR subunit for nicotine dependence and smoking therapy effectiveness with varenicline.
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Caton M, Ochoa ELM, Barrantes FJ. The role of nicotinic cholinergic neurotransmission in delusional thinking. NPJ SCHIZOPHRENIA 2020; 6:16. [PMID: 32532978 PMCID: PMC7293341 DOI: 10.1038/s41537-020-0105-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Accepted: 05/15/2020] [Indexed: 02/07/2023]
Abstract
Delusions are a difficult-to-treat and intellectually fascinating aspect of many psychiatric illnesses. Although scientific progress on this complex topic has been challenging, some recent advances focus on dysfunction in neural circuits, specifically in those involving dopaminergic and glutamatergic neurotransmission. Here we review the role of cholinergic neurotransmission in delusions, with a focus on nicotinic receptors, which are known to play a part in some illnesses where these symptoms appear, including delirium, schizophrenia spectrum disorders, bipolar disorder, Parkinson, Huntington, and Alzheimer diseases. Beginning with what we know about the emergence of delusions in these illnesses, we advance a hypothesis of cholinergic disturbance in the dorsal striatum where nicotinic receptors are operative. Striosomes are proposed to play a central role in the formation of delusions. This hypothesis is consistent with our current knowledge about the mechanism of action of cholinergic drugs and with our abstract models of basic cognitive mechanisms at the molecular and circuit levels. We conclude by pointing out the need for further research both at the clinical and translational levels.
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Affiliation(s)
- Michael Caton
- The Permanente Medical Group, Kaiser Santa Rosa Department of Psychiatry, 2235 Mercury Way, Santa Rosa, CA, 95047, USA
- Heritage Oaks Hospital, 4250 Auburn Boulevard, Sacramento, CA, 95841, USA
| | - Enrique L M Ochoa
- Heritage Oaks Hospital, 4250 Auburn Boulevard, Sacramento, CA, 95841, USA
- Volunteer Clinical Faculty, Department of Psychiatry and Behavioral Sciences, University of California at Davis, 2230 Stockton Boulevard, Sacramento, CA, 95817, USA
| | - Francisco J Barrantes
- Laboratory of Molecular Neurobiology, Institute for Biomedical Research (BIOMED), Faculty of Medical Sciences, UCA-CONICET, Av. Alicia Moreau de Justo 1600, C1107AFF, Buenos Aires, Argentina.
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7
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Animal models of liability to post-traumatic stress disorder: going beyond fear memory. Behav Pharmacol 2020; 30:122-129. [PMID: 30724805 DOI: 10.1097/fbp.0000000000000475] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
In this review, we advocate a dimensional approach on the basis of candidate endophenotypes to the development of animal models of post-traumatic stress disorder (PTSD) capable of including genetic liability factors, variations in symptoms profile and underlying neurobiological mechanisms, and specific comorbidities. Results from the clinical literature pointed to two candidate endophenotypes of PTSD: low sensory gating and high waiting impulsivity. Findings of comparative studies in mice of two inbred strains characterized by different expressions of the two candidate endophenotypes showed different strain-specific neural and behavioral effects of stress experiences. Thus, mice of the standard C57BL/6J strain show stress-induced helplessness, stress-learned helplessness, and stress-extinction-resistant conditioned freezing. Instead, mice of the genetically unrelated DBA/2J strain, expressing both candidate endophenotypes, show stress-induced extinction-resistant avoidance and neural and behavioral phenotypes promoted by prolonged exposure to addictive drugs. These strain differences are in line with evidence of associations between genetic variants and specific stress-promoted pathological profiles in PTSD, support a role of genotype in determining different PTSD comorbidities, and offer the means to investigate specific pathogenic processes.
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8
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McClain L, Segreti AM, Nau S, Shaw P, Finegold DN, Pan LA, Peters DG. Chromosome 15q13.3 microduplications are associated with treatment refractory major depressive disorder. GENES BRAIN AND BEHAVIOR 2019; 19:e12628. [PMID: 31828948 DOI: 10.1111/gbb.12628] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Revised: 11/18/2019] [Accepted: 12/02/2019] [Indexed: 12/25/2022]
Abstract
Major depressive disorder (MDD) affects approximately 15 million Americans. Approximately 2 million of these are classified as being refractory to treatment (TR-MDD). Because of the lack of available therapies for TR-MDD, and the high risk of suicide, there is interest in identifying new treatment modalities and diagnostic methods. Understanding of the impact of genomic copy number variation in the etiology of a variety of neuropsychiatric phenotypes is increasing. Low copy repeat elements at 15q13.3 facilitate non-allelic homologous recombination, resulting in recurrent copy number variants (CNVs). Numerous reports have described association between microdeletions in this region and a variety of neuropsychiatric phenotypes, with CHRNA7 implicated as a candidate gene. However, the pathogenicity of 15q13.3 duplications is less clear. As part of an ongoing study, in which we have identified a number of metabolomic anomalies in spinal fluid from TR-MDD patients, we also evaluated genomic copy number variation in patients (n = 125) and controls (n = 26) via array-based copy number genomic hybridization (CGH); the case frequency was compared with frequencies reported in a prior study as well as a larger population-sized cohort. We identified five TR-MDD patients with microduplications involving CHRNA7. CHRNA7 duplications are the most common CNVs identified by clinical CGH in this cohort. Therefore, this study provides insight into the potential involvement of CHRNA7 duplications in the etiology of TR-MDD and informs those involved with care of affected individuals.
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Affiliation(s)
- Lora McClain
- Department of Psychiatry, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Anna M Segreti
- Department of Psychiatry, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Sharon Nau
- Department of Psychiatry, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Patricia Shaw
- Magee-Womens Research Institute and Foundation, Pittsburgh, Pennsylvania
| | - David N Finegold
- Department of Human Genetics, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Lisa A Pan
- Department of Psychiatry, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania.,Department of Human Genetics, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - David G Peters
- Department of Psychiatry, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania.,Magee-Womens Research Institute and Foundation, Pittsburgh, Pennsylvania.,Department of Human Genetics, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania.,Department of Obstetrics, Gynecology and Reproductive Sciences, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
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9
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Solvang SEH, Nordrehaug JE, Aarsland D, Lange J, Ueland PM, McCann A, Midttun Ø, Tell GS, Giil LM. Kynurenines, Neuropsychiatric Symptoms, and Cognitive Prognosis in Patients with Mild Dementia. Int J Tryptophan Res 2019; 12:1178646919877883. [PMID: 31632053 PMCID: PMC6769202 DOI: 10.1177/1178646919877883] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Accepted: 08/31/2019] [Indexed: 01/13/2023] Open
Abstract
Introduction: Circulating tryptophan (Trp) and its downstream metabolites, the kynurenines,
are potentially neuroactive. Consequently, they could be associated with
neuropsychiatric symptoms and cognitive prognosis in patients with
dementia. Objective: The objective of this study was to assess associations between circulating
kynurenines, cognitive prognosis, and neuropsychiatric symptoms. Methods: We measured baseline serum Trp, neopterin, pyridoxal 5′-phosphate (PLP), and
9 kynurenines in 155 patients with mild dementia (90 with Alzheimer’s
disease, 65 with Lewy body dementia). The ratios between kynurenine and Trp
and kynurenic acid (KA) to kynurenine (KKR) were calculated. The Mini-Mental
State Examination (MMSE) and the Neuropsychiatric Inventory (NPI) were
administered at baseline and annually over 5 years. Associations between
baseline metabolite concentrations with MMSE and the NPI total score were
assessed using a generalized structural equation model (mixed-effects
multiprocess model), adjusted for age, sex, current smoking, glomerular
filtration rate, and PLP. Post hoc associations between KKRs and individual
NPI items were assessed using logistic mixed-effects models. False discovery
rate (0.05)–adjusted P values (Q values)
are reported. Results: Kynurenine had a nonlinear quadratic relationship with the intercept of the
MMSE scores over 5 years (Q < 0.05), but not with the
slope of MMSE decline. Kynurenine was associated with a higher NPI total
score over time (Q < 0.001). Post hoc, both KKR and KA
were associated with more hallucinations (Q < 0.05). Conclusions: Kynurenine has a complex relationship with cognition, where both low and high
levels were associated with poor cognitive performance. A higher KKR
indicated risk for neuropsychiatric symptoms, especially hallucinations.
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Affiliation(s)
- Stein-Erik Hafstad Solvang
- Department of Internal Medicine, Haraldsplass Deaconess Hospital, Bergen, Norway.,Department of Clinical Science, University of Bergen, Bergen, Norway
| | - Jan Erik Nordrehaug
- Department of Internal Medicine, Haraldsplass Deaconess Hospital, Bergen, Norway.,Department of Clinical Science, University of Bergen, Bergen, Norway
| | - Dag Aarsland
- Department of Old Age Psychiatry, King's College University, London, UK
| | - Johannes Lange
- The Norwegian Centre for Movement Disorders, Stavanger University Hospital, Stavanger, Norway.,Centre for Organelle Research (CORE), University of Stavanger, Stavanger, Norway
| | | | | | | | - Grethe S Tell
- Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway.,Division of Mental and Physical Health, Norwegian Institute of Public Health, Bergen, Norway
| | - Lasse Melvaer Giil
- Department of Internal Medicine, Haraldsplass Deaconess Hospital, Bergen, Norway.,Department of Clinical Science, University of Bergen, Bergen, Norway
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10
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de la Salle S, Inyang L, Impey D, Smith D, Choueiry J, Nelson R, Heera J, Baddeley A, Ilivitsky V, Knott V. Acute separate and combined effects of cannabinoid and nicotinic receptor agonists on MMN-indexed auditory deviance detection in healthy humans. Pharmacol Biochem Behav 2019; 184:172739. [PMID: 31283908 DOI: 10.1016/j.pbb.2019.172739] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 07/04/2019] [Accepted: 07/05/2019] [Indexed: 12/21/2022]
Abstract
The high prevalence of concomitant cannabis and nicotine use has implications for sensory and cognitive processing. While nicotine tends to enhance function in these domains, cannabis use has been associated with both sensory and cognitive impairments, though the underlying mechanisms are unclear. Additionally, the interaction of the nicotinic (nAChR) and cannabinoid (CB1) receptor systems has received limited study in terms of sensory/cognitive processes. This study involving healthy volunteers assessed the acute separate and combined effects of nabilone (a CB1 agonist) and nicotine on sensory processing as assessed by auditory deviance detection and indexed by the mismatch negativity (MMN) event-related potential. It was hypothesized that nabilone would impair auditory discriminability as shown by diminished MMN amplitudes, but not when administered in combination with nicotine. 20 male non-smokers and non-cannabis-users were assessed using a 5-stimulus 'optimal' multi-feature MMN paradigm within a randomized, placebo controlled design (placebo; nabilone [0.5 mg]; nicotine [6 mg]; and nicotine + nabilone). Treatment effects were region- and deviant-dependent. At the temporal regions (mastoid sites), MMN was reduced by nabilone and nicotine separately, whereas co-administration resulted in no impairment. At the frontal region, MMN was enhanced by co-administration of nicotine and nabilone, with no MMN effects being found with separate treatment. These neural effects have relevance for sensory/cognitive processes influenced by separate and simultaneous use of cannabis and tobacco and may have treatment implications for disorders associated with sensory dysfunction and impairments in endocannabinoid and nicotinic cholinergic neurotransmission.
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Affiliation(s)
- Sara de la Salle
- University of Ottawa Institute of Mental Health Research, Ottawa, ON, Canada; School of Psychology, University of Ottawa, Ottawa, ON, Canada
| | - Lawrence Inyang
- Interdisciplinary Sciences, Carleton University, Ottawa, ON, Canada
| | - Danielle Impey
- University of Ottawa Institute of Mental Health Research, Ottawa, ON, Canada; School of Psychology, University of Ottawa, Ottawa, ON, Canada
| | - Dylan Smith
- University of Ottawa Institute of Mental Health Research, Ottawa, ON, Canada; Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, Canada
| | - Joelle Choueiry
- University of Ottawa Institute of Mental Health Research, Ottawa, ON, Canada; Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, Canada
| | - Renee Nelson
- Biomedical Sciences, University of Ottawa, Ottawa, ON, Canada
| | - Jasmit Heera
- School of Psychology, University of Ottawa, Ottawa, ON, Canada
| | - Ashley Baddeley
- University of Ottawa Institute of Mental Health Research, Ottawa, ON, Canada
| | - Vadim Ilivitsky
- Department of Psychiatry, University of Ottawa, Ottawa, ON, Canada
| | - Verner Knott
- University of Ottawa Institute of Mental Health Research, Ottawa, ON, Canada; School of Psychology, University of Ottawa, Ottawa, ON, Canada; Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, Canada; Department of Psychiatry, University of Ottawa, Ottawa, ON, Canada.
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11
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Voss P, Thomas ME, Guercio GD, de Villers-Sidani E. Dysregulation of auditory neuroplasticity in schizophrenia. Schizophr Res 2019; 207:3-11. [PMID: 29703662 DOI: 10.1016/j.schres.2018.04.025] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Revised: 04/10/2018] [Accepted: 04/13/2018] [Indexed: 12/16/2022]
Abstract
Schizophrenia is a complex brain syndrome characterized by an array of positive symptoms (delusions, hallucinations, disorganized speech), negative symptoms (alogia, apathy, avolition) and cognitive impairments (memory, executive functions). Although investigations of the cognitive deficits in schizophrenia have primarily concentrated on disturbances affecting higher-order cognitive processes, there is an increasing realization that schizophrenia also affects early sensory processing, which might, in fact, play a significant role in the development of higher-order cognitive impairments. Recent evidence suggests that many of these early sensory processing impairments possibly arise from a dysregulation of plasticity regulators in schizophrenia, resulting in either reduced plasticity or excessive unregulated plasticity. The purpose of the present manuscript is to provide a concise overview of how the dysregulation of cortical plasticity mechanisms contributes to schizophrenia symptoms with an emphasis on auditory dysplasticity and to discuss its relevance for treatment outcomes. The idea that plasticity mechanisms are not constrained only within sensitive periods suggests that many functional properties of sensory neurons can be altered throughout the lifetime.
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Affiliation(s)
- Patrice Voss
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC H3A 2B4, Canada.
| | - Maryse E Thomas
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC H3A 2B4, Canada
| | - Gerson D Guercio
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC H3A 2B4, Canada
| | - Etienne de Villers-Sidani
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC H3A 2B4, Canada.
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12
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Li Y, Hou CL, Ma XR, Zang Y, Jia FJ, Lai KYC, Ungvari GS, Ng CH, Cai MY, Xiang YT. Nicotine dependence in community-dwelling Chinese patients with schizophrenia. Gen Psychiatr 2019; 32:e100014. [PMID: 31179421 PMCID: PMC6551433 DOI: 10.1136/gpsych-2018-100014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Revised: 11/16/2018] [Accepted: 11/25/2018] [Indexed: 12/13/2022] Open
Abstract
Background Smoking is a serious public health problem. Patients with schizophrenia usually have a higher prevalence of smoking than the general population, but the level of nicotine dependence is seldom studied, especially for patients living in the communities. Aims This study aimed to examine the level of nicotine dependence in Chinese community-dwelling patients with schizophrenia and explored its associated sociodemographic and clinical factors. Methods A total of 621 patients with schizophrenia treated in the primary care centres of Guangzhou were consecutively recruited. The level of nicotine dependence was assessed with the Chinese version of the Fagerström Test for Nicotine Dependence (FTND). Results 148 patients with schizophrenia were current smokers, and the mean (SD) score of FTND was 5.06 (2.55) for all the current smokers. The prevalence of nicotine addiction was 48.0% (95% CI: 40.0%-56.0%) in patients with current smoking. The patients with schizophrenia had a significantly higher level of nicotine dependence than the Chinese general population. Multiple linear regression analysis revealed that male gender, being unemployed, having a family history of psychiatric disorders, having major medical conditions, first illness episode and less severe positive symptoms were significantly associated with a higher level of nicotine dependence. Conclusion Community-dwelling patients with schizophrenia in China, especially male patients, had a higher level of nicotine dependence than the general population.
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Affiliation(s)
- Yan Li
- The National Clinical Research Center for Mental Disorders & Beijing Key Laboratory of Mental Disorders, Beijing Anding Hospital & the Advanced Innovation Center for Human Brain Protection, Capital Medical University, School of Mental Health, Beijing, China
| | - Cai-Lan Hou
- Guangdong Mental Health Center, Guangdong General Hospital and Guangdong Academy of Medical Sciences, Guangzhou, China
| | - Xin-Rong Ma
- Ningxia Mental Health Center, Ningxia Ning-An Hospital, Ningxia, China
| | - Yu Zang
- Shenzhen Key Laboratory for Psychological Healthcare, Shenzhen Institute of Mental Health, Shenzhen Kangning Hospital & Shenzhen Mental Health Center, Shenzhen, China
| | - Fu-Jun Jia
- Guangdong Mental Health Center, Guangdong General Hospital and Guangdong Academy of Medical Sciences, Guangzhou, China
| | - Kelly Y C Lai
- Department of Psychiatry, The Chinese University of Hong Kong, Hong Kong, China
| | - Gabor S Ungvari
- The University of Notre Dame Australia/Marian Centre, Perth, Australia
| | - Chee H Ng
- Department of Psychiatry, University of Melbourne, Melbourne, Victoria, Australia
| | - Mei-Ying Cai
- Guangzhou Yuexiu Center for Disease Control and Prevention, Guangdong, China
| | - Yu-Tao Xiang
- Unit of Psychiatry, Institute of Translational Medicine, Faculty of Health Sciences, University of Macau, Macao SAR, China
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13
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Choueiry J, Blais CM, Shah D, Smith D, Fisher D, Labelle A, Knott V. Combining CDP-choline and galantamine, an optimized α7 nicotinic strategy, to ameliorate sensory gating to speech stimuli in schizophrenia. Int J Psychophysiol 2019; 145:70-82. [PMID: 30790597 DOI: 10.1016/j.ijpsycho.2019.02.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Revised: 01/04/2019] [Accepted: 02/12/2019] [Indexed: 11/18/2022]
Abstract
Neural α7 nicotinic acetylcholine receptor (nAChR) expression and functioning deficits have been extensively associated with cognitive and early sensory gating (SG) impairments in schizophrenia (SCZ) patients and their relatives. SG, the suppression of irrelevant and redundant stimuli, is measured in a conditioning-testing (S1-S2) paradigm eliciting electroencephalography-derived P50 event-related potentials (ERPs), the S2 amplitudes of which are typically suppressed relative to S1. Despite extensive reports of nicotine-related improvements and several decades of research, an efficient nicotinic treatment has yet to be approved for SCZ. Following reports of SG improvements in low P50 suppressing SCZ patients and healthy participants with the α7 agonist, CDP-choline, this pilot study examined the combined modulatory effect of CDP-choline (500 mg) and galantamine (16 mg), a nAChR positive allosteric modulator and acetylcholinesterase inhibitor, on SG to speech stimuli in twenty-four SCZ patients in a randomized, double-blind and placebo-controlled design. As expected, in low P50 suppressors CDP-choline/galantamine (vs. Placebo) improved rP50 and dP50 scores by increasing inhibitory mechanisms as reflected by S2P50 amplitude reductions. Results also suggest a moderating role for auditory verbal hallucinations in treatment response. These preliminary findings provide supportive evidence for the involvement of α7 nAChR activity in speech gating in SCZ and support additional trials, examining different dose combinations and repeated doses of this optimized and personalized targeted α7 cholinergic treatment for SG dysfunction in subgroups of SCZ patients.
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Affiliation(s)
- Joelle Choueiry
- Department of Neuroscience, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada
| | - Crystal M Blais
- Institute of Cognitive Science, Carleton University, Ottawa, ON, Canada
| | - Dhrasti Shah
- School of Psychology, Faculty of Social Sciences, University of Ottawa, Ottawa, ON, Canada
| | - Dylan Smith
- School of Psychology, Faculty of Social Sciences, University of Ottawa, Ottawa, ON, Canada
| | - Derek Fisher
- Department of Psychology, Faculty of Social Sciences, Mount Saint Vincent University, Halifax, NS, Canada
| | - Alain Labelle
- The Royal Ottawa Mental Health Centre, Ottawa, ON, Canada
| | - Verner Knott
- Department of Neuroscience, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada; Institute of Cognitive Science, Carleton University, Ottawa, ON, Canada; School of Psychology, Faculty of Social Sciences, University of Ottawa, Ottawa, ON, Canada; Department of Psychology, Faculty of Social Sciences, Mount Saint Vincent University, Halifax, NS, Canada; The Royal Ottawa Mental Health Centre, Ottawa, ON, Canada; University of Ottawa Institute of Mental Health Research, Ottawa, ON, Canada.
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14
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Gillentine MA, White JJ, Grochowski CM, Lupski JR, Schaaf CP, Calarge CA, Calarge CA. CHRNA7 copy number gains are enriched in adolescents with major depressive and anxiety disorders. J Affect Disord 2018; 239:247-252. [PMID: 30029151 PMCID: PMC6273479 DOI: 10.1016/j.jad.2018.07.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Revised: 05/15/2018] [Accepted: 07/07/2018] [Indexed: 12/19/2022]
Abstract
OBJECTIVE Neuronal nicotinic acetylcholine receptors (nAChRs), specifically the α7 nAChR encoded by the gene CHRNA7, have been implicated in behavior regulation in animal models. In humans, copy number variants (CNVs) of CHRNA7 are found in a range of neuropsychiatric disorders, including mood and anxiety disorders. Here, we aimed to determine the prevalence of CHRNA7 CNVs among adolescents and young adults with major depressive disorder (MDD) and anxiety disorders. METHODS Twelve to 21 year-old participants with MDD and/or anxiety disorders (34% males, mean ± std age: 18.9 ± 1.8 years) were assessed for CHRNA7 copy number state using droplet digital PCR (ddPCR) and genomic quantitative PCR (qPCR). Demographic, anthropometric, and clinical data, including the Beck Anxiety Index (BAI), Beck Depression Inventory (BDI), and the Inventory of Depressive Symptoms (IDS) were collected and compared across individuals with and without a CHRNA7 CNV. RESULTS Of 205 individuals, five (2.4%) were found to carry a CHRNA7 gain, significantly higher than the general population. No CHRNA7 deletions were identified. Clinically, the individuals carrying CHRNA7 duplications did not differ significantly from copy neutral individuals with MDD and/or anxiety disorders. CONCLUSIONS CHRNA7 gains are relatively prevalent among young individuals with MDD and anxiety disorders (odds ratio = 4.032) without apparent distinguishing clinical features. Future studies should examine the therapeutic potential of α7 nAChR targeting drugs to ameliorate depressive and anxiety disorders.
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Affiliation(s)
- Madelyn A. Gillentine
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas.,Jan and Dan Neurological Research Institute, Texas Children’s Hospital, Houston, Texas
| | - Janson J. White
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas
| | | | - James R. Lupski
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas.,Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas.,Texas Children’s Hospital, Houston, Texas
| | - Christian P. Schaaf
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas.,Jan and Dan Neurological Research Institute, Texas Children’s Hospital, Houston, Texas
| | - Chadi A. Calarge
- Menninger Department of Psychiatry and Behavioral Sciences, Baylor College of Medicine, Houston, Texas
| | - Chadi A Calarge
- Menninger Department of Psychiatry and Behavioral Sciences, Baylor College of Medicine, Houston, TX 77030, United States.
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15
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Davies W. SULFATION PATHWAYS: The steroid sulfate axis and its relationship to maternal behaviour and mental health. J Mol Endocrinol 2018; 61:T199-T210. [PMID: 29440314 DOI: 10.1530/jme-17-0219] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Accepted: 11/16/2017] [Indexed: 12/14/2022]
Abstract
Steroid hormones can exist in functionally dissociable sulfated and non-sulfated (free) forms and can exert profound effects on numerous aspects of mammalian physiology; the ratio of free-to-sulfated steroids is governed by the antagonistic actions of steroid sulfatase (STS) and sulfotransferase (SULT) enzymes. Here, I examine evidence from human and animal model studies, which suggests that STS and its major substrate (dehydroepiandrosterone sulfate, DHEAS) and product (DHEA) can influence brain function, behaviour and mental health, before summarising how the activity of this axis varies throughout mammalian pregnancy and the postpartum period. I then consider how the steroid sulfate axis might impact upon normal maternal behaviour and how its dysfunction might contribute towards risk of postpartum psychiatric illness. Understanding the biological substrates underlying normal and abnormal maternal behaviour will be important for maximising the wellbeing of new mothers and their offspring.
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Affiliation(s)
- William Davies
- School of PsychologyCardiff University, Cardiff, UK
- Medical Research Council Centre for Neuropsychiatric Genetics and Genomics and Division of Psychological Medicine and Clinical NeurosciencesSchool of Medicine, Cardiff University, Cardiff, UK
- Neuroscience and Mental Health Research InstituteCardiff University, Cardiff, UK
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16
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Yohn SE, Conn PJ. Positive allosteric modulation of M 1 and M 4 muscarinic receptors as potential therapeutic treatments for schizophrenia. Neuropharmacology 2018; 136:438-448. [PMID: 28893562 PMCID: PMC5844786 DOI: 10.1016/j.neuropharm.2017.09.012] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2017] [Revised: 09/06/2017] [Accepted: 09/08/2017] [Indexed: 01/22/2023]
Abstract
Current antipsychotic drugs provide symptomatic relief for positive symptoms of schizophrenia, but do not offer symptom management for negative and cognitive symptoms. In addition, many patients discontinue treatment due to adverse side effects. Therefore, there is a critical need to develop more effective and safe treatment options. Although the etiology of schizophrenia is unclear, considerable data from post-mortem, neuroimaging and neuropharmacology studies support a role of the muscarinic acetylcholine (mAChRs) in the pathophysiology of schizophrenia. Substantial evidence suggests that activation of mAChRs has the potential to treat all symptom domains of schizophrenia. Despite encouraging results in demonstrating efficacy, clinical trials of nonselective mAChR agonists were limited in their clinical utility due to dose-limiting peripheral side effects. Accordingly, efforts have been made to specifically target centrally located M1 and M4 mAChR subtypes devoid of adverse-effect liability. To circumvent this limitation, there have been tremendous advances in the discovery of ligands that bind at allosteric sites, binding sites distinct from the orthosteric site, which are structurally less conserved and thereby afford high levels of receptor subtype selectivity. The discovery of subtype-specific allosteric modulators has greatly advanced our understanding of the physiological role of various muscarinic receptor subtypes in schizophrenia and the potential utility of M1 and M4 mAChR subtypes as targets for the development of novel treatments for schizophrenia and related disorders. This article is part of the Special Issue entitled 'Neuropharmacology on Muscarinic Receptors'.
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Affiliation(s)
- Samantha E Yohn
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, United States; Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN 37232, United States
| | - P Jeffrey Conn
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, United States; Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN 37232, United States.
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17
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Noda Y, Barr MS, Zomorrodi R, Cash RFH, Rajji TK, Farzan F, Chen R, George TP, Daskalakis ZJ, Blumberger DM. Reduced Short-Latency Afferent Inhibition in Prefrontal but not Motor Cortex and Its Association With Executive Function in Schizophrenia: A Combined TMS-EEG Study. Schizophr Bull 2018; 44:193-202. [PMID: 28379529 PMCID: PMC5768054 DOI: 10.1093/schbul/sbx041] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
BACKGROUND Cholinergic dysfunction is increasingly assumed to be involved in the pathophysiology of schizophrenia. Short-latency afferent inhibition (SAI) is a transcranial magnetic stimulation (TMS) paradigm that has been shown to assay central cholinergic activity from the motor cortex (M1). Recently, we established a method to index SAI from the dorsolateral prefrontal cortex (DLPFC), an area implicated in the pathophysiology of schizophrenia. We investigated SAI in M1 and DLPFC in schizophrenia. We hypothesized that modulation of N100 on TMS-evoked potentials (TEPs) from the DLPFC would be attenuated in patients with schizophrenia compared to healthy controls. METHODS SAI was examined in 12 patients, whose age was matched to controls, using TMS combined with electroencephalography (EEG). SAI was recorded with TMS applied to left M1 (M1-SAI) and DLPFC (DLPFC-SAI). For group comparison, we used the SAI data of healthy participants in our previous study. RESULTS In patients, N100 TEP was significantly attenuated with DLPFC-SAI, whereas P180 TEP was significantly increased with M1-SAI. Between patients and controls, there were significant differences in modulation of P180 TEP by M1-SAI (t22 = -2.748, P = .012; patients > controls) and N100 TEP by DLPFC-SAI (t22 = 5.456, P < .0001; patients < controls). Further, modulation of N100 TEP by DLPFC-SAI significantly correlated with executive function (r = -.740, P = .006, N = 12). CONCLUSION Our findings suggest that DLPFC-SAI but not M1-SAI were reduced in patients with schizophrenia and this was linked to deficits in cognition. This may reflect prefrontal cholinergic deficits and represent a biomarker for cholinergic and executive dysfunction in patients with schizophrenia.
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Affiliation(s)
- Yoshihiro Noda
- Temerty Centre for Therapeutic Brain Intervention, Centre for Addiction and Mental Health, Toronto, ON, Canada
- Department of Psychiatry, University of Toronto, Toronto, ON, Canada
| | - Mera S Barr
- Temerty Centre for Therapeutic Brain Intervention, Centre for Addiction and Mental Health, Toronto, ON, Canada
- Department of Psychiatry, University of Toronto, Toronto, ON, Canada
- Addictions Division, Centre for Addiction and Mental Health, Toronto, ON, Canada
| | - Reza Zomorrodi
- Temerty Centre for Therapeutic Brain Intervention, Centre for Addiction and Mental Health, Toronto, ON, Canada
- Department of Psychiatry, University of Toronto, Toronto, ON, Canada
| | - Robin F H Cash
- Division of Neurology, Department of Medicine, University of Toronto, Toronto, ON, Canada
- Division of Brain, Imaging and Behaviour—Systems Neuroscience, Krembil Research Institute, University Health Network, Toronto, ON, Canada
- Monash Alfred Psychiatry Research Centre, Monash University Central Clinical School and The Alfred, Melbourne, Australia
| | - Tarek K Rajji
- Temerty Centre for Therapeutic Brain Intervention, Centre for Addiction and Mental Health, Toronto, ON, Canada
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON, Canada
| | - Faranak Farzan
- Temerty Centre for Therapeutic Brain Intervention, Centre for Addiction and Mental Health, Toronto, ON, Canada
- Department of Psychiatry, University of Toronto, Toronto, ON, Canada
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON, Canada
| | - Robert Chen
- Division of Neurology, Department of Medicine, University of Toronto, Toronto, ON, Canada
- Division of Brain, Imaging and Behaviour—Systems Neuroscience, Krembil Research Institute, University Health Network, Toronto, ON, Canada
| | - Tony P George
- Department of Psychiatry, University of Toronto, Toronto, ON, Canada
- Addictions Division, Centre for Addiction and Mental Health, Toronto, ON, Canada
| | - Zafiris J Daskalakis
- Temerty Centre for Therapeutic Brain Intervention, Centre for Addiction and Mental Health, Toronto, ON, Canada
- Department of Psychiatry, University of Toronto, Toronto, ON, Canada
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON, Canada
| | - Daniel M Blumberger
- Temerty Centre for Therapeutic Brain Intervention, Centre for Addiction and Mental Health, Toronto, ON, Canada
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON, Canada
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18
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Calabrò M, Porcelli S, Crisafulli C, Wang SM, Lee SJ, Han C, Patkar AA, Masand PS, Albani D, Raimondi I, Forloni G, Bin S, Cristalli C, Mantovani V, Pae CU, Serretti A. Genetic Variants Within Molecular Targets of Antipsychotic Treatment: Effects on Treatment Response, Schizophrenia Risk, and Psychopathological Features. J Mol Neurosci 2018; 64:62-74. [PMID: 29164477 DOI: 10.1007/s12031-017-1002-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Accepted: 11/14/2017] [Indexed: 12/14/2022]
Abstract
Schizophrenia (SCZ) is a common and severe mental disorder. Genetic factors likely play a role in its pathophysiology as well as in treatment response. In the present study, we investigated the effects of several single nucleotide polymorphisms (SNPs) within 9 genes involved with antipsychotic (AP) mechanisms of action. Two independent samples were recruited. The Korean sample included 176 subjects diagnosed with SCZ and 326 healthy controls, while the Italian sample included 83 subjects and 194 controls. AP response as measured by the positive and negative syndrome scale (PANSS) was the primary outcome, while the secondary outcome was the SCZ risk. Exploratory analyses were performed on (1) symptom clusters response (as measured by PANSS subscales); (2) age of onset; (3) family history; and (4) suicide history. Associations evidenced in the primary analyses did not survive to the FDR correction. Concerning SCZ risk, we partially confirmed the associations among COMT and MAPK1 genetic variants and SCZ. Finally, our exploratory analysis suggested that CHRNA7 and HTR2A genes may modulate both positive and negative symptoms responses, while PLA2G4A and SIGMAR1 may modulate respectively positive and negative symptoms responses. Moreover, GSK3B, HTR2A, PLA2G4A, and S100B variants may determine an anticipation of SCZ age of onset. Our results did not support a primary role for the genes investigated in AP response as a whole. However, our exploratory findings suggested that these genes may be involved in symptom clusters response.
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Affiliation(s)
- Marco Calabrò
- Department of Biomedical and Dental Sciences and Morphofunctional Images, Division of Medical Biotechnologies and Preventive Medicine, University of Messina, Messina, Italy
| | - Stefano Porcelli
- Department of Biomedical and NeuroMotor Sciences, University of Bologna, Bologna, Italy
| | - Concetta Crisafulli
- Department of Biomedical and Dental Sciences and Morphofunctional Images, Division of Medical Biotechnologies and Preventive Medicine, University of Messina, Messina, Italy
| | - Sheng-Min Wang
- Department of Psychiatry, The Catholic University of Korea College of Medicine, Seoul, Republic of Korea
| | - Soo-Jung Lee
- Department of Psychiatry, The Catholic University of Korea College of Medicine, Seoul, Republic of Korea
| | - Changsu Han
- Department of Psychiatry, Korea University, College of Medicine, Seoul, Republic of Korea
| | - Ashwin A Patkar
- Department of Psychiatry and Behavioral Sciences, Duke University Medical Center, Durham, NC, USA
| | - Prakash S Masand
- Global Medical Education, New York, NY, USA
- Academic Medicine Education Institute, Duke-NUS Medical School, Singapore, Singapore
| | - Diego Albani
- Department of Neuroscience, IRCCS - Istituto di Ricerche Farmacologiche Mario Negri, Milan, Italy
| | - Ilaria Raimondi
- Department of Neuroscience, IRCCS - Istituto di Ricerche Farmacologiche Mario Negri, Milan, Italy
| | - Gianluigi Forloni
- Department of Neuroscience, IRCCS - Istituto di Ricerche Farmacologiche Mario Negri, Milan, Italy
| | - Sofia Bin
- Center for Applied Biomedical Research (CRBA, St. Orsola University Hospital, Bologna, Italy
| | - Carlotta Cristalli
- Center for Applied Biomedical Research (CRBA, St. Orsola University Hospital, Bologna, Italy
| | - Vilma Mantovani
- Center for Applied Biomedical Research (CRBA, St. Orsola University Hospital, Bologna, Italy
| | - Chi-Un Pae
- Department of Psychiatry, The Catholic University of Korea College of Medicine, Seoul, Republic of Korea.
- Department of Psychiatry and Behavioral Sciences, Duke University Medical Center, Durham, NC, USA.
- Department of Psychiatry, Bucheon St. Mary's Hospital, The Catholic University of Korea College of Medicine, 2 Sosa-Dong, Wonmi-Gu, Bucheon, Kyeonggi-Do, 420-717, Republic of Korea.
- Cell Death Disease Research Center, College of Medicine, The Catholic University of Korea, Seoul, Korea.
| | - Alessandro Serretti
- Department of Biomedical and NeuroMotor Sciences, University of Bologna, Bologna, Italy
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19
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Bueno-Junior LS, Simon NW, Wegener MA, Moghaddam B. Repeated Nicotine Strengthens Gamma Oscillations in the Prefrontal Cortex and Improves Visual Attention. Neuropsychopharmacology 2017; 42:1590-1598. [PMID: 28128335 PMCID: PMC5518895 DOI: 10.1038/npp.2017.15] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Revised: 12/14/2016] [Accepted: 12/22/2016] [Indexed: 11/18/2022]
Abstract
Nicotine has strong addictive as well as procognitive properties. While a large body of research on nicotine continues to inform us about mechanisms related to its reinforcing effects, less is known about clinically relevant mechanisms that subserve its cognitive-enhancing properties. Understanding the latter is critical for developing optimal strategies for treating cognitive deficits. The primary brain region implicated in cognitive functions improved by nicotine is the prefrontal cortex (PFC). Here we assessed the impact of nicotine on unit activity and local field potential oscillations in the PFC of behaving rats. An acute dose of nicotine produced a predominantly inhibitory influence on population activity, a small increase in gamma oscillations, and a decrease in theta and beta oscillations. After a daily dosing regimen, a shift to excitatory-inhibitory balance in single-unit activity and stronger gamma oscillations began to emerge. This pattern of plasticity was specific to the gamma band as lower frequency oscillations were suppressed consistently across daily nicotine treatments. Gamma oscillations are associated with enhanced attentional capacity. Consistent with this mechanism, the repeat dosing regimen in a separate cohort of subjects led to improved performance in an attention task. These data suggest that procognitive effects of nicotine may involve development of enhanced gamma oscillatory activity and a shift to excitatory-inhibitory balance in PFC neural activity. In the context of the clinical use of nicotine and related agonists for treating cognitive deficits, these data suggest that daily dosing may be critical to allow for development of robust gamma oscillations.
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Affiliation(s)
- Lezio S Bueno-Junior
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA, USA,Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil
| | - Nicholas W Simon
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA, USA
| | - Meredyth A Wegener
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA, USA
| | - Bita Moghaddam
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA, USA,Department of Behavioral Neuroscience, Oregon Health and Science University, L470 3181, S.W. Sam Jackson Park Rd., Portland OR 97239, USA, Tel: 503 402 2858, E-mail:
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20
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Partial agonism at the α7 nicotinic acetylcholine receptor improves attention, impulsive action and vigilance in low attentive rats. Eur Neuropsychopharmacol 2017; 27:325-335. [PMID: 28161246 DOI: 10.1016/j.euroneuro.2017.01.013] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Revised: 01/09/2017] [Accepted: 01/18/2017] [Indexed: 11/23/2022]
Abstract
Inattention is a disabling symptom in conditions such as schizophrenia and attention deficit/hyperactivity disorder. Nicotine can improve attention and vigilance, but is unsuitable for clinical use due to abuse liability. Genetic knockout of the α7 nicotinic acetylcholine receptor (nAChR) induces attention deficits therefore selective agonism may improve attention, without the abuse liability associated with nicotine. The α7 nAChR partial agonist encenicline (formerly EVP-6124) enhances memory in rodents and humans. Here we investigate, for the first time, efficacy of encenicline to improve attention and vigilance in animals behaviourally grouped for low attentive traits in the 5 choice-continuous performance task (5C-CPT). Female Lister Hooded rats were trained to perform the 5C-CPT with a variable stimulus duration (SD). Animals were then grouped based on performance into upper and lower quartiles of d' (vigilance) and accuracy (selective attention), producing high-attentive (HA) and low-attentive (LA) groups. LA animals showed an increase in selective attention and vigilance at 0.3mg/kg encenicline, a reduction in impulsive action (probability of false alarms) and increase in vigilance following 1mg/kg at 0.75sSD. At 1mg/kg, HA animals had reduced selective attention at 0.75sSD and reduced vigilance at 0.75 and 1.25sSD. Improvement of attention, vigilance and impulsive action in LA animals demonstrates that encenicline has pro-attentive properties dependent on baseline levels of performance. Our work suggests that α7 nAChR partial agonism may improve attention particularly in conditions with low attention.
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21
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Peterson DJ, Gill WD, Dose JM, Hoover DB, Pauly JR, Cummins ED, Burgess KC, Brown RW. The effects of nicotine in the neonatal quinpirole rodent model of psychosis: Neural plasticity mechanisms and nicotinic receptor changes. Behav Brain Res 2017; 325:17-24. [PMID: 28235586 DOI: 10.1016/j.bbr.2017.02.029] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Revised: 02/16/2017] [Accepted: 02/18/2017] [Indexed: 01/06/2023]
Abstract
Neonatal quinpirole (NQ) treatment to rats increases dopamine D2 receptor sensitivity persistent throughout the animal's lifetime. In Experiment 1, we analyzed the role of α7 and α4β2 nicotinic receptors (nAChRs) in nicotine behavioral sensitization and on the brain-derived neurotrophic factor (BDNF) response to nicotine in NQ- and neonatally saline (NS)-treated rats. In Experiment 2, we analyzed changes in α7 and α4β2 nAChR density in the nucleus accumbens (NAcc) and dorsal striatum in NQ and NS animals sensitized to nicotine. Male and female Sprague-Dawley rats were neonatally treated with quinpirole (1mg/kg) or saline from postnatal days (P)1-21. Animals were given ip injections of either saline or nicotine (0.5mg/kg free base) every second day from P33 to P49 and tested on behavioral sensitization. Before each injection, animals were ip administered the α7 nAChR antagonist methyllycaconitine (MLA; 2 or 4mg/kg) or the α4β2 nAChR antagonist dihydro beta erythroidine (DhβE; 1 or 3mg/kg). Results revealed NQ enhanced nicotine sensitization that was blocked by DhβE. MLA blocked the enhanced nicotine sensitization in NQ animals, but did not block nicotine sensitization. NQ enhanced the NAcc BDNF response to nicotine which was blocked by both antagonists. In Experiment 2, NQ enhanced nicotine sensitization and enhanced α4β2, but not α7, nAChR upregulation in the NAcc. These results suggest a relationship between accumbal BDNF and α4β2 nAChRs and their role in the behavioral response to nicotine in the NQ model which has relevance to schizophrenia, a behavioral disorder with high rates of tobacco smoking.
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Affiliation(s)
- Daniel J Peterson
- Department of Psychology, East Tennessee State University, Johnson City, TN 37614, United States
| | - W Drew Gill
- Department of Biomedical Sciences, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN 37614, United States
| | - John M Dose
- Department of Psychology, St. Norbert College, De Pere, WI, 54115,United States
| | - Donald B Hoover
- Department of Biomedical Sciences, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN 37614, United States
| | - James R Pauly
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY 40536, United States
| | - Elizabeth D Cummins
- Department of Psychology, East Tennessee State University, Johnson City, TN 37614, United States
| | - Katherine C Burgess
- Department of Biomedical Sciences, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN 37614, United States
| | - Russell W Brown
- Department of Biomedical Sciences, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN 37614, United States.
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22
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Chuhma N, Mingote S, Kalmbach A, Yetnikoff L, Rayport S. Heterogeneity in Dopamine Neuron Synaptic Actions Across the Striatum and Its Relevance for Schizophrenia. Biol Psychiatry 2017; 81:43-51. [PMID: 27692238 PMCID: PMC5121049 DOI: 10.1016/j.biopsych.2016.07.002] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Revised: 07/03/2016] [Accepted: 07/07/2016] [Indexed: 02/06/2023]
Abstract
Brain imaging has revealed alterations in dopamine uptake, release, and receptor levels in patients with schizophrenia that have been resolved on the scale of striatal subregions. However, the underlying synaptic mechanisms are on a finer scale. Dopamine neuron synaptic actions vary across the striatum, involving variations not only in dopamine release but also in dopamine neuron connectivity, cotransmission, modulation, and activity. Optogenetic studies have revealed that dopamine neurons release dopamine in a synaptic signal mode, and that the neurons also release glutamate and gamma-aminobutyric acid as cotransmitters, with striking regional variation. Fast glutamate and gamma-aminobutyric acid cotransmission convey discrete patterns of dopamine neuron activity to striatal neurons. Glutamate may function not only in a signaling role at a subset of dopamine neuron synapses, but also in mediating vesicular synergy, contributing to regional differences in loading of dopamine into synaptic vesicles. Regional differences in dopamine neuron signaling are likely to be differentially involved in the schizophrenia disease process and likely determine the subregional specificity of the action of psychostimulants that exacerbate the disorder, and antipsychotics that ameliorate the disorder. Elucidating dopamine neuron synaptic signaling offers the potential for achieving greater pharmacological specificity through intersectional pharmacological actions targeting subsets of dopamine neuron synapses.
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Affiliation(s)
- Nao Chuhma
- Department of Psychiatry, Columbia University, New York, New York; Department of Molecular Therapeutics, NYS Psychiatric Institute, New York, New York
| | - Susana Mingote
- Department of Psychiatry, Columbia University, New York, New York; Department of Molecular Therapeutics, NYS Psychiatric Institute, New York, New York
| | - Abigail Kalmbach
- Department of Psychiatry, Columbia University, New York, New York; Department of Molecular Therapeutics, NYS Psychiatric Institute, New York, New York
| | - Leora Yetnikoff
- Department of Psychiatry, Columbia University, New York, New York; Department of Molecular Therapeutics, NYS Psychiatric Institute, New York, New York
| | - Stephen Rayport
- Department of Psychiatry, Columbia University, New York, New York; Department of Molecular Therapeutics, NYS Psychiatric Institute, New York, New York.
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The challenge of reducing smoking in people with serious mental illness. THE LANCET RESPIRATORY MEDICINE 2016; 4:835-844. [DOI: 10.1016/s2213-2600(16)30228-4] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Revised: 07/18/2016] [Accepted: 07/19/2016] [Indexed: 12/28/2022]
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Saur T, Cohen BM, Ma Q, Babb SM, Buttner EA, Yao WD. Acute and chronic effects of clozapine on cholinergic transmission in cultured mouse superior cervical ganglion neurons. J Neurogenet 2016; 30:297-305. [PMID: 27627024 PMCID: PMC6061957 DOI: 10.1080/01677063.2016.1229779] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Revised: 08/18/2016] [Accepted: 08/24/2016] [Indexed: 10/21/2022]
Abstract
Cholinergic dysfunction contributes to cognitive deficits in schizophrenia. The atypical antipsychotic clozapine improves cognition in patients with schizophrenia, possibly through modulation of the cholinergic system. However, little is known about specific underlying mechanisms. We investigated the acute and chronic effects of clozapine on cholinergic synaptic transmission in cultured superior cervical ganglion (SCG) neurons. Spontaneous excitatory postsynaptic currents (sEPSCs) were detected and were reversibly inhibited by the nicotinic receptor antagonist d-tubocurarine, confirming that the synaptic responses were primarily mediated by nicotinic receptors. Bath application of clozapine at therapeutic concentrations rapidly and reversely inhibited both the amplitude and frequency of sEPSCs in a concentration-dependent manner, without changing either rise or decay time, suggesting that clozapine effects have both presynaptic and postsynaptic origins. The acute effects of clozapine on sEPSCs were recapitulated by chronic treatment of SCG cultures with similar concentrations of clozapine, as clozapine treatment for 4 d reduced the frequency and amplitude of sEPSCs without affecting their kinetics. Cell survival analysis indicated that SCG neuron cell counts after chronic clozapine treatment were comparable to the control group. These results demonstrate that therapeutic concentrations of clozapine suppress nicotinic synaptic transmission in SCG cholinergic synapses, a simple in vitro preparation of cholinergic transmission.
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Affiliation(s)
- Taixiang Saur
- a McLean Hospital/Harvard Medical School , Belmont , MA , USA
| | - Bruce M Cohen
- a McLean Hospital/Harvard Medical School , Belmont , MA , USA
| | - Qi Ma
- b New England Primate Research Center, Harvard Medical School , Southborough , MA , USA
| | - Suzann M Babb
- a McLean Hospital/Harvard Medical School , Belmont , MA , USA
| | - Edgar A Buttner
- a McLean Hospital/Harvard Medical School , Belmont , MA , USA
| | - Wei-Dong Yao
- b New England Primate Research Center, Harvard Medical School , Southborough , MA , USA
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25
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Reyes-Parada M, Iturriaga-Vasquez P. The development of novel polypharmacological agents targeting the multiple binding sites of nicotinic acetylcholine receptors. Expert Opin Drug Discov 2016; 11:969-81. [DOI: 10.1080/17460441.2016.1227317] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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26
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Ascoli BM, Géa LP, Colombo R, Barbé-Tuana FM, Kapczinski F, Rosa AR. The role of macrophage polarization on bipolar disorder: Identifying new therapeutic targets. Aust N Z J Psychiatry 2016; 50:618-30. [PMID: 27091850 DOI: 10.1177/0004867416642846] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Bipolar disorder is a chronic, severe and disabling disease; however, its pathophysiology remains poorly understood. Recent evidence has suggested that inflammation and immune dysregulation play a significant role in the pathophysiology of bipolar disorder. This review is aimed to highlight the importance of systemic inflammation in modulating the inflammatory response of microglia and hence its potential involvement with bipolar disorder. We also discuss novel therapeutic strategies that emerge from this new research. METHOD This article presents a theoretical synthesis of the effects of systemic inflammation on the immune response of the central nervous system in bipolar disorder. The complex relationship between stress, pro-inflammatory cytokines and microglial dysfunction is summarized, emphasizing the role of the kynurenine pathway in this process and, consequently, their effects on neuronal plasticity. RESULTS Bipolar patients demonstrate increased serum levels of pro-inflammatory cytokines (interleukin-1β, interleukin-6 and tumor necrosis factor-α) and lower hypothalamic-pituitary-adrenal axis sensitivity. This imbalance in the immune system promotes a change in blood-brain barrier permeability, leading to an inflammatory signal spread in the central nervous system from the periphery, through macrophages activation (M1 polarization). Chronic microglial activation can result in neuronal apoptosis, neurogenesis inhibition, hippocampal volume reduction, lower neurotransmitters synthesis and cytotoxicity, by increasing glutamate production and kynurenine metabolism. CONCLUSIONS This review provides an overview of the mechanisms involved in the immune system imbalance and its potential involvement in the pathophysiology of bipolar disorder. Consequently, new strategies that normalize the immune-inflammatory pathways may provide a valuable therapeutic target for the treatment of these disorders.
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Affiliation(s)
- Bruna M Ascoli
- Laboratory of Molecular Psychiatry, Hospital de Clínicas de Porto Alegre (HCPA), Porto Alegre, Brazil Postgraduate Program in Psychiatry and Behavioral Science, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Brazil
| | - Luiza P Géa
- Laboratory of Molecular Psychiatry, Hospital de Clínicas de Porto Alegre (HCPA), Porto Alegre, Brazil Postgraduate Program in Pharmacology and Therapeutics, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Brazil
| | - Rafael Colombo
- Laboratory of Molecular Psychiatry, Hospital de Clínicas de Porto Alegre (HCPA), Porto Alegre, Brazil Laboratory of Pharmacology and Physiology, Universidade de Caxias do Sul (UCS), Caxias do Sul, Brazil
| | - Florência M Barbé-Tuana
- Laboratory of Molecular Biology and Bioinformatics, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Brazil Postgraduate Program in Biochemistry, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Brazil
| | - Flávio Kapczinski
- Laboratory of Molecular Psychiatry, Hospital de Clínicas de Porto Alegre (HCPA), Porto Alegre, Brazil Postgraduate Program in Psychiatry and Behavioral Science, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Brazil Department of Psychiatry, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Brazil
| | - Adriane Ribeiro Rosa
- Laboratory of Molecular Psychiatry, Hospital de Clínicas de Porto Alegre (HCPA), Porto Alegre, Brazil Postgraduate Program in Psychiatry and Behavioral Science, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Brazil Postgraduate Program in Pharmacology and Therapeutics, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Brazil Department of Pharmacology, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Brazil
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Bespalov A, Müller R, Relo AL, Hudzik T. Drug Tolerance: A Known Unknown in Translational Neuroscience. Trends Pharmacol Sci 2016; 37:364-378. [DOI: 10.1016/j.tips.2016.01.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Revised: 01/27/2016] [Accepted: 01/28/2016] [Indexed: 02/08/2023]
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Parikh V, Kutlu MG, Gould TJ. nAChR dysfunction as a common substrate for schizophrenia and comorbid nicotine addiction: Current trends and perspectives. Schizophr Res 2016; 171:1-15. [PMID: 26803692 PMCID: PMC4762752 DOI: 10.1016/j.schres.2016.01.020] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Revised: 01/07/2016] [Accepted: 01/10/2016] [Indexed: 11/18/2022]
Abstract
INTRODUCTION The prevalence of tobacco use in the population with schizophrenia is enormously high. Moreover, nicotine dependence is found to be associated with symptom severity and poor outcome in patients with schizophrenia. The neurobiological mechanisms that explain schizophrenia-nicotine dependence comorbidity are not known. This study systematically reviews the evidence highlighting the contribution of nicotinic acetylcholine receptors (nAChRs) to nicotine abuse in schizophrenia. METHODS Electronic data bases (Medline, Google Scholar, and Web of Science) were searched using the selected key words that match the aims set forth for this review. A total of 276 articles were used for the qualitative synthesis of this review. RESULTS Substantial evidence from preclinical and clinical studies indicated that dysregulation of α7 and β2-subunit containing nAChRs account for the cognitive and affective symptoms of schizophrenia and nicotine use may represent a strategy to remediate these symptoms. Additionally, recent meta-analyses proposed that early tobacco use may itself increase the risk of developing schizophrenia. Genetic studies demonstrating that nAChR dysfunction that may act as a shared vulnerability factor for comorbid tobacco dependence and schizophrenia were found to support this view. The development of nAChR modulators was considered an effective therapeutic strategy to ameliorate psychiatric symptoms and to promote smoking cessation in schizophrenia patients. CONCLUSIONS The relationship between schizophrenia and smoking is complex. While the debate for the self-medication versus addiction vulnerability hypothesis continues, it is widely accepted that a dysfunction in the central nAChRs represent a common substrate for various symptoms of schizophrenia and comorbid nicotine dependence.
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Affiliation(s)
- Vinay Parikh
- Department of Psychology and Neuroscience Program, Temple University, Philadelphia, PA 19112, United States.
| | - Munir Gunes Kutlu
- Department of Psychology and Neuroscience Program, Temple University, Philadelphia, PA 19112, United States
| | - Thomas J Gould
- Department of Psychology and Neuroscience Program, Temple University, Philadelphia, PA 19112, United States
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Tregellas JR, Smucny J, Legget KT, Stevens KE. Effects of a ketogenic diet on auditory gating in DBA/2 mice: A proof-of-concept study. Schizophr Res 2015; 169:351-354. [PMID: 26453015 PMCID: PMC4827327 DOI: 10.1016/j.schres.2015.09.022] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Revised: 09/18/2015] [Accepted: 09/21/2015] [Indexed: 11/20/2022]
Abstract
Although the ketogenic diet has shown promise in a pilot study and case report in schizophrenia, its effects in animal models of hypothesized disease mechanisms are unknown. This study examined effects of treatment with the ketogenic diet on hippocampal P20/N40 gating in DBA/2 mice, a translational endophenotype that mirrors inhibitory deficits in P50 sensory gating in schizophrenia patients. As expected, the diet increased blood ketone levels. Animals with the highest ketone levels showed the lowest P20/N40 gating ratios. These preliminary results suggest that the ketogenic diet may effectively target sensory gating deficits and is a promising area for additional research in schizophrenia.
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Affiliation(s)
- Jason R Tregellas
- Research Service, Denver VA Medical Center, Denver, CO, USA; Neuroscience Program, University of Colorado Anschutz Medical Campus, Aurora, CO, USA; Department of Psychiatry, University of Colorado Anschutz Medical Campus, Aurora, CO, USA.
| | - Jason Smucny
- Neuroscience Program, University of Colorado Anschutz Medical Campus, Aurora, CO, USA; Department of Psychiatry, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Kristina T Legget
- Neuroscience Program, University of Colorado Anschutz Medical Campus, Aurora, CO, USA; Department of Psychiatry, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Karen E Stevens
- Department of Psychiatry, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
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Multiple binding sites in the nicotinic acetylcholine receptors: An opportunity for polypharmacolgy. Pharmacol Res 2015; 101:9-17. [PMID: 26318763 DOI: 10.1016/j.phrs.2015.08.018] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Revised: 08/20/2015] [Accepted: 08/20/2015] [Indexed: 12/21/2022]
Abstract
For decades, the development of selective compounds has been the main goal for chemists and biologists involved in drug discovery. However, diverse lines of evidence indicate that polypharmacological agents, i.e. those that act simultaneously at various protein targets, might show better profiles than selective ligands, regarding both efficacy and side effects. On the other hand, the availability of the crystal structure of different receptors allows a detailed analysis of the main interactions between drugs and receptors in a specific binding site. Neuronal nicotinic acetylcholine receptors (nAChRs) constitute a large and diverse family of ligand-gated ion channels (LGICs) that, as a product of its modulation, regulate neurotransmitter release, which in turns produce a global neuromodulation of the central nervous system. nAChRs are pentameric protein complexes in such a way that expression of compatible subunits can lead to various receptor assemblies or subtypes. The agonist binding site, located at the extracellular region, exhibits different properties depending on the subunits that conform the receptor. In the last years, it has been recognized that nAChRs could also contain one or more allosteric sites which could bind non-classical nicotinic ligands including several therapeutically useful drugs. The presence of multiple binding sites in nAChRs offers an interesting possibility for the development of novel polypharmacological agents with a wide spectrum of actions.
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Wong DF, Kuwabara H, Pomper M, Holt DP, Brasic JR, George N, Frolov B, Willis W, Gao Y, Valentine H, Nandi A, Gapasin L, Dannals RF, Horti AG. Human brain imaging of α7 nAChR with [(18)F]ASEM: a new PET radiotracer for neuropsychiatry and determination of drug occupancy. Mol Imaging Biol 2015; 16:730-8. [PMID: 25145965 DOI: 10.1007/s11307-014-0779-3] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
PURPOSE Using the α7-nAChR radiotracer, [(18)F]ASEM, we present the first successful human positron emission tomography (PET) studies. Rodent occupancy with three clinically employed α7-nAChR drugs confirms the specificity of the radiotracer. PROCEDURES Five healthy male subjects were imaged for 90 min following IV [(18)F]ASEM. Two subjects were scanned for the second time (test/retest; TRV). Mouse biodistribution of [(18)F]ASEM was carried out in CD1 mice injected with using human equivalent doses of DMXB-A, EVP-6124, and varenicline to block specific binding. RESULTS [(18)F]ASEM readily entered the brain and peaked at 15 min post-injection with reversible kinetics and a peak %SUV of about 400 %. The regional human brain distribution of [(18)F]ASEM matched previous in vitro data and baboon PET results. The precuneus, parietal, occipital, cingulate cortexes, putamen, and thalamus showed high values of distribution volume (>20 ml/ml) and binding potentials >1 with TRV averaged 10.8 ± 5.1 %. In mouse distribution studies, there was significant dose-dependent blockade in the mouse brain with DMXB-A as well as the other two α7-nAChR drugs. CONCLUSIONS The characteristics of [(18)F]ASEM are consistent with the ability to quantify α7-nAChR in the human brain. [(18)F]ASEM is suitable for imaging neuropsychiatric disorders and target engagement (receptor occupancy) of potential α7-nAChR drugs.
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Affiliation(s)
- Dean F Wong
- Department of Radiology, School of Medicine, The Johns Hopkins University, Baltimore, MD, USA,
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Martínez A, Gaspar PA, Hillyard SA, Bickel S, Lakatos P, Dias EC, Javitt DC. Neural oscillatory deficits in schizophrenia predict behavioral and neurocognitive impairments. Front Hum Neurosci 2015; 9:371. [PMID: 26190988 PMCID: PMC4486865 DOI: 10.3389/fnhum.2015.00371] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Accepted: 06/12/2015] [Indexed: 11/13/2022] Open
Abstract
Paying attention to visual stimuli is typically accompanied by event-related desynchronizations (ERD) of ongoing alpha (7-14 Hz) activity in visual cortex. The present study used time-frequency based analyses to investigate the role of impaired alpha ERD in visual processing deficits in schizophrenia (Sz). Subjects viewed sinusoidal gratings of high (HSF) and low (LSF) spatial frequency (SF) designed to test functioning of the parvo- vs. magnocellular pathways, respectively. Patients with Sz and healthy controls paid attention selectively to either the LSF or HSF gratings which were presented in random order. Event-related brain potentials (ERPs) were recorded to all stimuli. As in our previous study, it was found that Sz patients were selectively impaired at detecting LSF target stimuli and that ERP amplitudes to LSF stimuli were diminished, both for the early sensory-evoked components and for the attend minus unattend difference component (the Selection Negativity), which is generally regarded as a specific index of feature-selective attention. In the time-frequency domain, the differential ERP deficits to LSF stimuli were echoed in a virtually absent theta-band phase locked response to both unattended and attended LSF stimuli (along with relatively intact theta-band activity for HSF stimuli). In contrast to the theta-band evoked responses which were tightly stimulus locked, stimulus-induced desynchronizations of ongoing alpha activity were not tightly stimulus locked and were apparent only in induced power analyses. Sz patients were significantly impaired in the attention-related modulation of ongoing alpha activity for both HSF and LSF stimuli. These deficits correlated with patients' behavioral deficits in visual information processing as well as with visually based neurocognitive deficits. These findings suggest an additional, pathway-independent, mechanism by which deficits in early visual processing contribute to overall cognitive impairment in Sz.
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Affiliation(s)
- Antígona Martínez
- Nathan Kline Institute for Psychiatric Research Orangeburg, NY, USA ; Department of Neurosciences, University of California, San Diego La Jolla, CA, USA
| | - Pablo A Gaspar
- Department of Psychiatry, School of Medicine, ICBM, University of Chile Santiago, Chile
| | - Steven A Hillyard
- Department of Neurosciences, University of California, San Diego La Jolla, CA, USA
| | - Stephan Bickel
- Department of Neurology, Albert Einstein College of Medicine Bronx, NY, USA
| | - Peter Lakatos
- Nathan Kline Institute for Psychiatric Research Orangeburg, NY, USA
| | - Elisa C Dias
- Nathan Kline Institute for Psychiatric Research Orangeburg, NY, USA
| | - Daniel C Javitt
- Nathan Kline Institute for Psychiatric Research Orangeburg, NY, USA ; Columbia University, College of Physician and Surgeons New York, NY, USA
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Smucny J, Stevens KE, Olincy A, Tregellas JR. Translational utility of rodent hippocampal auditory gating in schizophrenia research: a review and evaluation. Transl Psychiatry 2015; 5:e587. [PMID: 26101850 PMCID: PMC4490287 DOI: 10.1038/tp.2015.77] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Revised: 04/14/2015] [Accepted: 05/04/2015] [Indexed: 01/15/2023] Open
Abstract
Impaired gating of the auditory evoked P50 potential is one of the most pharmacologically well-characterized features of schizophrenia. This deficit is most commonly modeled in rodents by implanted electrode recordings from the hippocampus of the rodent analog of the P50, the P20-N40. The validity and effectiveness of this tool, however, has not been systematically reviewed. Here, we summarize findings from studies that have examined the effects of pharmacologic modulation on gating of the rodent hippocampal P20-N40 and the human P50. We show that drug effects on the P20-N40 are highly predictive of human effects across similar dose ranges. Furthermore, mental status (for example, anesthetized vs alert) does not appear to diminish the predictive capacity of these recordings. We then discuss hypothesized neuropharmacologic mechanisms that may underlie gating effects for each drug studied. Overall, this review supports continued use of hippocampal P20-N40 gating as a translational tool for schizophrenia research.
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Affiliation(s)
- J Smucny
- Neuroscience Program, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
- Research Service, Denver VA Medical Center, Denver, CO, USA
- Department of Psychiatry, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - K E Stevens
- Department of Psychiatry, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - A Olincy
- Research Service, Denver VA Medical Center, Denver, CO, USA
- Department of Psychiatry, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - J R Tregellas
- Neuroscience Program, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
- Research Service, Denver VA Medical Center, Denver, CO, USA
- Department of Psychiatry, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
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Knott V, Impey D, Choueiry J, Smith D, de la Salle S, Saghir S, Smith M, Beaudry E, Ilivitsky V, Labelle A. An acute dose, randomized trial of the effects of CDP-Choline on Mismatch Negativity (MMN) in healthy volunteers stratified by deviance detection level. ACTA ACUST UNITED AC 2015. [DOI: 10.1186/s40810-014-0002-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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Magnussen JH, Ettrup A, Donat CK, Peters D, Pedersen MHF, Knudsen GM, Mikkelsen JD. Radiosynthesis and in vitro validation of (3)H-NS14492 as a novel high affinity alpha7 nicotinic receptor radioligand. Eur J Pharmacol 2015; 762:35-41. [PMID: 25941084 DOI: 10.1016/j.ejphar.2015.04.036] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Revised: 04/22/2015] [Accepted: 04/23/2015] [Indexed: 11/30/2022]
Abstract
The neuronal α7 nicotinic acetylcholine receptor is a homo-pentameric ligand-gated ion channel that is a promising drug target for cognitive deficits in Alzheimer׳s disease and schizophrenia. We have previously described (11)C-NS14492 as a suitable agonist radioligand for in vivo positron emission tomography (PET) occupancy studies of the α7 nicotinic receptor in the pig brain. In order to investigate the utility of the same compound for in vitro studies, (3)H-NS14492 was synthesized and its binding properties were characterized using in vitro autoradiography and homogenate binding assays in pig frontal cortex. (3)H-NS14492 showed specific binding to α7 nicotinic receptors in autoradiography, revealing a dissociation constant (Kd) of 2.1±0.7nM and a maximum number of binding sites (Bmax) of 15.7±2.0fmol/mg tissue equivalent. Binding distribution was similar to that of another selective ligand (125)I-α-bungarotoxin ((125)I-BTX) in autoradiography, and unlabeled NS14492 displaced (125)I-BTX with an inhibition constant (Ki) of 23nM. (3)H-NS14492 bound to α7 nicotinic receptors in homogenized pig frontal cortex with a Kd of 0.8±0.3nM and a Bmax of 30.2±11.6fmol/mg protein. This binding assay further revealed the Ki rank order for a number of α7 nicotinic receptor agonists, and positive allosteric modulators (PAMs). Further, we saw increased binding of (3)H-NS14492 to pig frontal cortex membranes when co-incubated with PNU-120596, a type II PAM. Taken together, these findings show that (3)H-NS14492 is a useful new in vitro radioligand for the pig α7 nicotinic receptor.
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Affiliation(s)
- Janus H Magnussen
- Neurobiology Research Unit, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Anders Ettrup
- Neurobiology Research Unit, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Cornelius K Donat
- Neurobiology Research Unit, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | | | - Martin H F Pedersen
- The Hevesy Laboratory, DTU Nutech, The Technical University of Denmark, Denmark
| | - Gitte M Knudsen
- Neurobiology Research Unit, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Jens D Mikkelsen
- Neurobiology Research Unit, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark.
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Valli M, Betti AH, Danuello A, Pivatto M, Centurião F, Antonio CB, Rates SMK, Bolzani VDS. Pyridinic analog of the natural product (−)-spectaline as potential adjuvant for the treatment of central nervous system disorders. Bioorg Med Chem Lett 2015; 25:2247-50. [DOI: 10.1016/j.bmcl.2015.02.050] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Revised: 02/16/2015] [Accepted: 02/20/2015] [Indexed: 12/28/2022]
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Bumb JM, Enning F, Leweke FM. Drug repurposing and emerging adjunctive treatments for schizophrenia. Expert Opin Pharmacother 2015; 16:1049-67. [PMID: 25866122 DOI: 10.1517/14656566.2015.1032248] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
INTRODUCTION Schizophrenia is a frequent disorder, which substantially impairs patients' quality of life. Moreover, the burden of illness for patients, their families and for the society, in general, is substantial. Nevertheless, the understanding of the pathophysiology of this syndrome, concise diagnostic methods and more effective and tolerable treatments are still lacking. Thus, innovative approaches and the exploration of new territories are required. AREAS COVERED An overview of repurposed drugs and emerging treatments for schizophrenia is presented, focusing on randomized, controlled trials and meta-analyses. EXPERT OPINION Despite many years of drug research, several needs in the treatment of schizophrenia including the safety and tolerability, stage-dependent and personalized approaches, as well as drug delivery and sustainability have not been addressed sufficiently. Given the current failure of a number of mechanistically new drugs, repurposed compounds may serve as alternative and/or adjunctive agents for schizophrenic patients and for treatment refractory patients in particular. Anti-inflammatory drugs (e.g., acetylsalicylic acid, celecoxib and minocycline), as well as N-acetylcysteine, a precursor of the major antioxidant glutathione, hormones (e.g., estrogen, raloxifene and oxytocin), glutamatergic (e.g., glycine and d-serine) and nicotinergic compounds, 'nutraceuticals' (e.g., ω-3 fatty acids) and cannabidiol, an endocannabinoidmodulator, represent promising agents in this field.
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Affiliation(s)
- Jan Malte Bumb
- Heidelberg University, Central Institute of Mental Health, Department of Psychiatry and Psychotherapy, Medical Faculty Mannheim , J5, 68159 Mannheim , Germany +49 621 1703 2321 ; +49 621 1703 2325 ;
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Stevens KE, Zheng L, Floyd KL, Stitzel JA. Maximizing the effect of an α7 nicotinic receptor PAM in a mouse model of schizophrenia-like sensory inhibition deficits. Brain Res 2015; 1611:8-17. [PMID: 25744161 DOI: 10.1016/j.brainres.2015.02.044] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Revised: 02/20/2015] [Accepted: 02/21/2015] [Indexed: 12/30/2022]
Abstract
Positive allosteric modulators (PAMs) for the α7 nicotinic receptor hold promise for the treatment of sensory inhibition deficits observed in schizophrenia patients. Studies of these compounds in the DBA/2 mouse, which models the schizophrenia-related deficit in sensory inhibition, have shown PAMs to be effective in improving the deficit. However, the first published clinical trial of a PAM for both sensory inhibition deficits and related cognitive difficulties failed, casting a shadow on this therapeutic approach. The present study used both DBA/2 mice, and C3H Chrna7 heterozygote mice to assess the ability of the α7 PAM, PNU-120596, to improve sensory inhibition. Both of these strains of mice have reduced hippocampal α7 nicotinic receptor numbers and deficient sensory inhibition similar to schizophrenia patients. Low doses of PNU-120596 (1 or 3.33mg/kg) were effective in the DBA/2 mouse but not the C3H Chrna7 heterozygote mouse. Moderate doses of the selective α7 nicotinic receptor agonist, choline chloride (10 or 33mg/kg), were also ineffective in improving sensory inhibition in the C3H Chrna7 heterozygote mouse. However, combining the lowest doses of both PNU-120596 and choline chloride in this mouse model did improve sensory inhibition. We propose here that the difference in efficacy of PNU-120596 between the 2 mouse strains is driven by differences in hippocampal α7 nicotinic receptor numbers, such that C3H Chrna7 heterozygote mice require additional direct stimulation of the α7 receptors. These data may have implications for further clinical testing of putative α7 nicotinic receptor PAMs.
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Affiliation(s)
- Karen E Stevens
- Department of Psychiatry, University of Colorado Denver, Anschutz Medical Campus, Aurora, CO, USA.
| | - Lijun Zheng
- Department of Psychiatry, University of Colorado Denver, Anschutz Medical Campus, Aurora, CO, USA
| | - Kirsten L Floyd
- Department of Psychiatry, University of Colorado Denver, Anschutz Medical Campus, Aurora, CO, USA
| | - Jerry A Stitzel
- Institute for Behavioral Genetics, University of Colorado, Boulder, Boulder, CO, USA
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Neurocognitive effects of acute choline supplementation in low, medium and high performer healthy volunteers. Pharmacol Biochem Behav 2015; 131:119-29. [PMID: 25681529 DOI: 10.1016/j.pbb.2015.02.004] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Revised: 01/20/2015] [Accepted: 02/04/2015] [Indexed: 12/28/2022]
Abstract
Novel pharmacological treatments targeting alpha 7 nicotinic acetylcholine receptor (α7 nAChR) hypofunction in schizophrenia have shown mixed success in ameliorating cognitive impairments associated with this disorder. Choline, a selective agonist at α7 receptors is increased with oral administration of cytidine 5'-diphosphocholine (CDP-choline), the cognitive effects of which were assessed in healthy volunteers. Using the CogState test battery, behavioral performance in schizophrenia-relevant cognitive domains was assessed in 24 male participants following a single low (500mg) and moderate (1000mg) dose of CDP-choline. Relative to placebo, CDP-choline improved processing speed, working memory, verbal learning, verbal memory, and executive function in low baseline performers, while exerting no effects in medium baseline performers, and diminishing cognition in high baseline performers. Dose effects varied with cognitive domain but were evident with both the 500mg and 1000mg doses. These preliminary findings of cognitive enhancement in relatively impaired performers are consistent with the α7 receptor mechanism and support further trials with CDP-choline as a potential pro-cognitive strategy for cognitive impairment in schizophrenia.
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40
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Rowe AR, Mercer L, Casetti V, Sendt KV, Giaroli G, Shergill SS, Tracy DK. Dementia praecox redux: a systematic review of the nicotinic receptor as a target for cognitive symptoms of schizophrenia. J Psychopharmacol 2015; 29:197-211. [PMID: 25567553 DOI: 10.1177/0269881114564096] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Most individuals with schizophrenia suffer some cognitive dysfunction: such deficits are predictive of longer-term functioning; and current dopamine-blocking antipsychotics have made little impact on this domain. There is a pressing need to develop novel pharmacological agents to tackle this insidious but most disabling of problems. The acetylcholinergic system is involved in cognitive and attentional processing, and its metabotropic and nicotinic receptors are widespread throughout the brain. Deficits in acetylcholinergic functioning occur in schizophrenia, and high rates of tobacco smoking have been posited to represent a form of self-medication. The nicotinic acetylcholine receptor (nAChR) has emerged as a putative target to improve cognitive deficits in schizophrenia, and this study systematically reviewed the emerging data. Nineteen studies were identified, covering three compound classes: agonists at the α7 and α 4β2 nAChRs, and positive allosteric modulators. Overall data are underwhelming: some studies showed significant improvements in cognition but as many studies had negative findings. It remains unclear if this represents drug limitations or nascent study methodology problems. The literature is particularly hindered by variability in inclusion of smokers, generally small sample sizes, and a lack of consensus on cognitive test batteries. Future work should evaluate longer-term outcomes, and, particularly, the effects of concomitant cognitive training.
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Affiliation(s)
- Arann R Rowe
- The Institute of Psychiatry, King's College London, London, UK
| | - Louise Mercer
- The Institute of Psychiatry, King's College London, London, UK
| | - Valentina Casetti
- The Institute of Psychiatry, King's College London, London, UK Oxleas NHS Foundation Trust, London, UK
| | | | | | - Sukhwinder S Shergill
- The Institute of Psychiatry, King's College London, London, UK South London and Maudsley NHS Foundation Trust, London, UK
| | - Derek K Tracy
- The Institute of Psychiatry, King's College London, London, UK Oxleas NHS Foundation Trust, London, UK
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Smucny J, Visani A, Tregellas JR. Could vagus nerve stimulation target hippocampal hyperactivity to improve cognition in schizophrenia? Front Psychiatry 2015; 6:43. [PMID: 25852579 PMCID: PMC4371554 DOI: 10.3389/fpsyt.2015.00043] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Accepted: 03/10/2015] [Indexed: 01/26/2023] Open
Affiliation(s)
- Jason Smucny
- Neuroscience Program, University of Colorado Anschutz Medical Campus , Aurora, CO , USA ; Research Service, Denver Veterans Affairs Medical Center , Denver, CO , USA ; Department of Psychiatry, University of Colorado Anschutz Medical Campus , Aurora, CO , USA
| | - Adrienne Visani
- Department of Psychiatry, University of Colorado Anschutz Medical Campus , Aurora, CO , USA
| | - Jason R Tregellas
- Neuroscience Program, University of Colorado Anschutz Medical Campus , Aurora, CO , USA ; Research Service, Denver Veterans Affairs Medical Center , Denver, CO , USA ; Department of Psychiatry, University of Colorado Anschutz Medical Campus , Aurora, CO , USA
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Javitt DC, Freedman R. Sensory processing dysfunction in the personal experience and neuronal machinery of schizophrenia. Am J Psychiatry 2015; 172:17-31. [PMID: 25553496 PMCID: PMC4501403 DOI: 10.1176/appi.ajp.2014.13121691] [Citation(s) in RCA: 263] [Impact Index Per Article: 29.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Sensory processing deficits, first investigated by Kraepelin and Bleuler as possible pathophysiological mechanisms in schizophrenia, are now being recharacterized in the context of our current understanding of the molecular and neurobiological brain mechanisms involved. The National Institute of Mental Health Research Domain Criteria position these deficits as intermediaries between molecular and cellular mechanisms and clinical symptoms of schizophrenia, such as hallucinations. The prepulse inhibition of startle responses by a weaker preceding tone, the inhibitory gating of response to paired sensory stimuli characterized using the auditory P50 evoked response, and the detection of slight deviations in patterns of sensory stimulation eliciting the cortical mismatch negativity potential demonstrate deficits in early sensory processing mechanisms, whose molecular and neurobiological bases are increasingly well understood. Deficits in sensory processing underlie more complex cognitive dysfunction and are in turn affected by higher-level cognitive difficulties. These deficits are now being used to identify genes involved in familial transmission of schizophrenia and to monitor potentially therapeutic drug effects for both treatment and prevention. This research also provides a clinical reminder that patients' sensory perception of the surrounding world, even during treatment sessions, may differ considerably from others' perceptions. A person's ability to understand and interact effectively with the surrounding world ultimately depends on an underlying sensory experience of it.
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Affiliation(s)
- Daniel C. Javitt
- Division of Experimental Therapeutics, Department of Psychiatry, Program in Cognitive Neuroscience and Schizophrenia, Nathan Kline Institute for Psychiatric Research/Columbia University Medical Center, New York, NY 10032, USA
| | - Robert Freedman
- Department of Psychiatry, University of Colorado Denver School of Medicine, Mail Stop F546, Aurora, CO, 80045, USA
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Hashimoto K. Targeting of α7 Nicotinic Acetylcholine Receptors in the Treatment of Schizophrenia and the Use of Auditory Sensory Gating as a Translational Biomarker. Curr Pharm Des 2015; 21:3797-806. [PMID: 26044974 PMCID: PMC5024727 DOI: 10.2174/1381612821666150605111345] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Accepted: 06/04/2015] [Indexed: 11/22/2022]
Abstract
Accumulating evidence suggests that the α7 subtype of nicotinic acetylcholine receptors (nAChRs) plays a key role in inflammatory processes, thought to be involved in the pathophysiology of neuropsychiatric diseases, such as schizophrenia and Alzheimer's disease. Preclinical and clinical studies showed that the diminished suppression of P50 auditory evoked potentials in patients with schizophrenia may be associated with a decreased density of α7 nAChRs in the brain. This points to a role for auditory sensory gating (P50) as a translational biomarker. A number of agonists and positive allosteric modulators (PAMs) for α7 nAChR promoted beneficial effects in animal models with sensory gating and cognitive deficits. Additionally, several clinical studies showed that α7 nAChR agonists could improve suppression in auditory P50 evoked potentials, as well as cognitive deficits, and negative symptoms in patients with schizophrenia. Taken together, α7 nAChR presents as an extremely attractive therapeutic target for schizophrenia. In this article, the author discusses recent findings on α7 nAChR agonists such as DMXB-A, RG3487, TC-5619, tropisetron, EVP-6124 (encenicline), ABT-126, AQW051 and α7 nAChR PAMs such as JNJ-39393406, PNU- 120596 and AVL-3288 (also known as UCI-4083), and their potential as therapeutic drugs for neuropsychiatric diseases, such as schizophrenia.
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Affiliation(s)
- Kenji Hashimoto
- Division of Clinical Neuroscience, Chiba University Center for Forensic, Mental Health, 1-8-1 Inohana, Chiba 260-8670, Japan.
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Knott V, Smith D, de la Salle S, Impey D, Choueiry J, Beaudry E, Smith M, Saghir S, Ilivitsky V, Labelle A. CDP-choline: effects of the procholine supplement on sensory gating and executive function in healthy volunteers stratified for low, medium and high P50 suppression. J Psychopharmacol 2014; 28:1095-108. [PMID: 25315828 DOI: 10.1177/0269881114553254] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Diminished auditory sensory gating and associated neurocognitive deficits in schizophrenia have been linked to altered expression and function of the alpha-7 nicotinic acetycholinergic receptor (α7 nAChR), the targeting of which may have treatment potential. Choline is a selective α7 nAChR agonist and the aim of this study was to determine whether cytidine 5'-diphosphocholine (CDP-choline), or citicoline, a dietary source of choline, increases sensory gating and cognition in healthy volunteers stratified for gating level. In a randomized, placebo-controlled, double-blind design involving acute administration of low, moderate doses (500 mg, 1000 mg) of CDP-choline, 24 healthy volunteers were assessed for auditory gating as indexed by suppression of the P50 event-related potential (ERP) in a paired-stimulus (S1, S2) paradigm, and for executive function as measured by the Groton Maze Learning Task (GMLT) of the CogState Schizophrenia Battery. CDP-choline improved gating (1000 mg) and suppression of the S2 P50 response (500 mg, 1000 mg), with the effects being selective for individuals with low gating (suppression) levels. Tentative support was also shown for increased GMLT performance (500 mg) in low suppressors. These preliminary findings with CDP-choline in a healthy, schizophrenia-like surrogate sample are consistent with a α7 nAChR mechanism and support further trials with choline as a pro-cognitive strategy.
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Affiliation(s)
- Verner Knott
- Institute of Mental Health Research, University of Ottawa, Ottawa, ON, Canada Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, Canada School of Psychology, University of Ottawa, Ottawa, ON, Canada Department of Psychiatry, University of Ottawa, Ottawa, ON, Canada
| | - Dylan Smith
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, Canada
| | | | - Danielle Impey
- School of Psychology, University of Ottawa, Ottawa, ON, Canada
| | - Joelle Choueiry
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, Canada
| | - Elise Beaudry
- School of Psychology, University of Ottawa, Ottawa, ON, Canada
| | - Meaghan Smith
- School of Psychology, University of Ottawa, Ottawa, ON, Canada
| | - Salman Saghir
- School of Psychology, University of Ottawa, Ottawa, ON, Canada
| | - Vadim Ilivitsky
- Department of Psychiatry, University of Ottawa, Ottawa, ON, Canada
| | - Alain Labelle
- Department of Psychiatry, University of Ottawa, Ottawa, ON, Canada
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Demars MP, Morishita H. Cortical parvalbumin and somatostatin GABA neurons express distinct endogenous modulators of nicotinic acetylcholine receptors. Mol Brain 2014; 7:75. [PMID: 25359633 PMCID: PMC4228157 DOI: 10.1186/s13041-014-0075-9] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2014] [Accepted: 10/17/2014] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Inhibition from GABAergic interneurons in brain circuits is a critical component of cognitive function. This inhibition is regulated through a diverse network of neuromodulation. A number of recent studies suggest that one of the major regulators of interneuron function is nicotinic acetylcholinergic transmission and dysregulation of both systems is common in psychiatric conditions. However, how nicotinic modulation impacts specific subpopulations of diverse GABAergic interneurons remains in question. One potential way of conferring specificity to the convergence of GABAergic and nicotinic signaling is through the expression of a unique family of nicotinic acetycholine receptor modulators, the Lynx family. The present study sought to identify members of the Lynx family enriched in cortical interneurons and to elucidate subpopulations of GABAergic neurons that express unique nicotinic modulators. RESULTS We utilize double fluorescence in situ hybridization to examine the interneuronal expression of the Lynx family in adult mouse visual cortex. We find that two of the Lynx family members, Lynx1 and Lypd6, are enriched in interneuron populations in cortex. Nearly all parvalbumin interneurons express Lynx1 but we did not detect Lypd6 in this population. Conversely, in somatostatin interneurons Lypd6 was found in a subset localized to deep cortical layers but no somatostatin neurons show detectable levels of Lynx1. Using a combination of genetic and viral manipulations we further show that a subpopulation of deep-layer cortico-cortical long-range somatostatin neurons also express Lypd6. CONCLUSIONS This work shows that distinct subpopulations of GABAergic interneurons express unique Lynx family members. The pattern of expression of Lynx family members within interneurons places them in a unique position to potentially regulate the convergence of GABAergic and nicotinic systems, dysfunction of which are characteristic of psychiatric disorders.
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Affiliation(s)
- Michael P Demars
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1230, New York, NY, 10029, USA. .,Department of Neuroscience, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY, 10029, USA. .,Department of Ophthalmology, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY, 10029, USA. .,Mindich Child Health and Development Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY, 10029, USA. .,Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY, 10029, USA.
| | - Hirofumi Morishita
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1230, New York, NY, 10029, USA. .,Department of Neuroscience, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY, 10029, USA. .,Department of Ophthalmology, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY, 10029, USA. .,Mindich Child Health and Development Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY, 10029, USA. .,Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY, 10029, USA.
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Hutson PH, Tarazi FI, Madhoo M, Slawecki C, Patkar AA. Preclinical pharmacology of amphetamine: Implications for the treatment of neuropsychiatric disorders. Pharmacol Ther 2014; 143:253-64. [DOI: 10.1016/j.pharmthera.2014.03.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Accepted: 03/14/2014] [Indexed: 11/28/2022]
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Knott V, Impey D, Philippe T, Smith D, Choueiry J, de la Salle S, Dort H. Modulation of auditory deviance detection by acute nicotine is baseline and deviant dependent in healthy nonsmokers: a mismatch negativity study. Hum Psychopharmacol 2014; 29:446-58. [PMID: 25196041 DOI: 10.1002/hup.2418] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Revised: 03/19/2014] [Accepted: 05/19/2014] [Indexed: 12/24/2022]
Abstract
OBJECTIVE Cognitive enhancement resulting from nicotinic acetylcholine receptor stimulation may be evidenced by increased efficiency of the auditory-frontal cortex network of auditory discrimination, which is impaired in schizophrenia, a cognitive disorder associated with excessive tobacco use. Investigating automatic (preattentive) detection of acoustic change with the mismatch negativity (MMN) brain event-related potential in response to nicotine in individuals with varying baseline levels of auditory discrimination may provide useful insight into the cholinergic regulation of this neural network and its potential amelioration with novel nicotinic agents. METHODS Sixty healthy, non-smoking male volunteers were presented with an 'optimal' multi-feature MMN paradigm in a randomized, placebo controlled double-blind design with 6 mg of nicotine gum. RESULTS Participants with low, medium, and high baseline amplitudes responded differently to nicotine (vs. placebo), and nicotine response was feature specific. Whereas MMN in individuals with high amplitudes was diminished by nicotine, MMN increased in those with low amplitudes. Nicotine effects were not shown in medium amplitude participants. CONCLUSIONS These findings provide preliminary support for the role of nicotinic neurotransmission in sensory memory processing of auditory change and suggest that nicotinic receptor modulation can both enhance and diminish change detection, depending on baseline MMN and its eliciting stimulus feature.
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Affiliation(s)
- Verner Knott
- University of Ottawa Institute of Mental Health Research, Ottawa, Ontario, Canada; School of Psychology, University of Ottawa, Ottawa, Ontario, Canada; Neuroscience Program, Department of Cellular and Molecular Medicine, University of Ottawa, Ontario, Canada
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Goktalay T, Buyukuysal S, Uslu G, Coskun AS, Yorgancioglu A, Kayir H, Uzbay T, Goktalay G. Varenicline disrupts prepulse inhibition only in high-inhibitory rats. Prog Neuropsychopharmacol Biol Psychiatry 2014; 53:54-60. [PMID: 24632394 DOI: 10.1016/j.pnpbp.2014.03.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Revised: 02/26/2014] [Accepted: 03/04/2014] [Indexed: 11/29/2022]
Abstract
Varenicline, a widely used smoking cessation drug, has partial agonistic activity at α4β2 nicotinic receptors, and full agonistic activity at α7 nicotinic receptors. Thus it may interact with cognitive processes and may alleviate some of the cognitive disturbances observed in psychotic illnesses such as schizophrenia. We aimed to test the effects of varenicline on sensorimotor gating functioning, which is crucial for normal cognitive processes, especially for the integration of sensory and cognitive information processing and the execution of appropriate motor responses. Prepulse inhibition (PPI) of the acoustic startle reflex was used to test the sensorimotor gating functioning. First, the effects of varenicline and nicotine on rats having high or low baseline PPI levels were evaluated; then, varenicline was applied prior to apomorphine (0.5 mg/kg), and MK-801 (0.15 mg/kg), which are used as comparative models of PPI disruption. Varenicline (0.5-3 mg/kg) did not change PPI when given alone in naïve animals. When rats were selected according to their baseline PPI values, varenicline (1 mg/kg) significantly decreased PPI in high-inhibitory (HI) but not in low-inhibitory (LI) rats. Nicotine (1 mg/kg; tartrate salt) produced a similar activity in LI and HI groups. In combination experiments, varenicline did not reverse either apomorphine or the MK-801-induced disruption of PPI. These results demonstrate that the effects of both varenicline and nicotine on sensorimotor gating are influenced by the baseline PPI levels. Moreover, varenicline has no effect on apomorphine or the MK-801-induced disruption of PPI.
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Affiliation(s)
- Tugba Goktalay
- Department of Chest Diseases, Faculty of Medicine, Celal Bayar University, Manisa, Turkey
| | - Sema Buyukuysal
- Department of Medical Pharmacology, Faculty of Medicine, Uludag University, Bursa, Turkey
| | - Gulsah Uslu
- Department of Medical Pharmacology, Faculty of Medicine, Uludag University, Bursa, Turkey
| | - Aysin S Coskun
- Department of Chest Diseases, Faculty of Medicine, Celal Bayar University, Manisa, Turkey
| | - Arzu Yorgancioglu
- Department of Chest Diseases, Faculty of Medicine, Celal Bayar University, Manisa, Turkey
| | - Hakan Kayir
- Department of Medical Pharmacology, Psychopharmacology Research Unit, Gulhane Military Medical Academy, Ankara, Turkey
| | - Tayfun Uzbay
- Neuropsychopharmacology Application and Research Center, Uskudar University, Istanbul, Turkey
| | - Gokhan Goktalay
- Department of Medical Pharmacology, Faculty of Medicine, Uludag University, Bursa, Turkey.
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Add-on clinical effects of selective antagonist of 5HT6 receptors AVN-211 (CD-008-0173) in patients with schizophrenia stabilized on antipsychotic treatment: pilot study. CNS Spectr 2014; 19:316-23. [PMID: 23768250 DOI: 10.1017/s1092852913000394] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
UNLABELLED The serotoninergic system as a target for add-on treatment seems to be a promising approach in patients with schizophrenia. OBJECTIVE To clarify if selective 5HT-6 antagonist AVN-211 (CD-008-0173) adds clinical and cognitive effects to stable antipsychotic treatment. METHODS A randomized, double-blind, placebo-controlled, add-on, 4r-week trial in 47 schizophrenia patients (21 patients receiving study drug and 26 receiving placebo) who were stabilized on antipsychotic medication was performed. Seventeen patients from the study drug group and 25 patients from the placebo group completed the trial. Treatment effects were measured using clinical rating scales and attention tests. RESULTS With no differences at baseline, there was a significant difference between the groups in Positive and Negative Syndrome Scale (PANSS) positive subscale score (p = 0.058) in favor of patients in the treatment group at the endpoint. The PANSS positive subscore (p = 0.0068) and Clinical Global Impression-Severity (CGI-S) (p = 0.048) score significantly changed only in the treatment group. Only in the placebo group were significant changes in Calgary Depression Rating Scale (CDRS) total score registered. The indices of attention tests at endpoint did not show differences between the groups, with the exception of the scope of change in the results of the subtest VIII of the Wechsler Adult Intelligence Scale (WAIS), which showed difference between the groups (p = 0.02) and was significantly larger in the treatment group. Only inside the study drug group, significant changes in selectivity and continuous attention were observed regarding total correct responses (p = 0.0038) and reaction time (p = 0.058) in the Continuous Attention Task (CAT) test. CONCLUSION Selective 5HT6 antagonist AVN-211 (CD-008-0173) added antipsychotic and some procognitive (attention) effects to antipsychotic medication.
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Neurocognitive endophenotypes in schizophrenia: modulation by nicotinic receptor systems. Prog Neuropsychopharmacol Biol Psychiatry 2014; 52:79-85. [PMID: 23871750 PMCID: PMC3851927 DOI: 10.1016/j.pnpbp.2013.07.010] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2013] [Revised: 07/05/2013] [Accepted: 07/08/2013] [Indexed: 11/24/2022]
Abstract
Cigarette smoking is the leading preventable cause of death in the Western world, with a considerably higher prevalence observed in schizophrenia compared to the general population. Despite the negative health consequences of smoking heavily, it has been proposed that individuals with schizophrenia may maintain smoking behaviors to remediate symptoms associated with the disorder. Neurocognitive deficits are a core feature of schizophrenia and are present in approximately 80% of patients. Further, these deficits constitute an endophenotype of schizophrenia, as they are stable across disease phases, and are heritable. The neurocognitive deficits that are present in schizophrenia are especially debilitating, since they are associated with poor clinical and functional outcomes and community integration. Interestingly, these deficits may also constitute a vulnerability factor towards the initiation and maintenance of tobacco use. Contributing to the potential shared vulnerability between schizophrenia and tobacco dependence is a dysregulation of the nicotinic acetylcholine receptor (nAChR) system. Pre-clinical evidence has shown that nicotine affects several neurotransmitter systems, including dopamine (DA), glutamate, and γ-aminobutyric acid (GABA), and certain neuropsychological deficits associated with these neurotransmitters (reaction time, spatial working memory, sustained attention, and sensory gating) are improved after nicotine administration in patients with schizophrenia. These positive effects on neurocognition appear to be more pronounced in smokers with schizophrenia, and may be an important mechanism that explains the co-morbidity of schizophrenia and tobacco dependence.
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