Schizophrenia as a disorder of too little dopamine: implications for symptoms and treatment

Characteristics and clinical correlates of risk symptoms in individuals at clinical high-risk for psychosis: A systematic review and meta-analysis

Emerging evidence suggests that the duration of risk symptoms (DUR) may have an impact on clinical outcomes in clinical high-risk for psychosis (CHRP) participants. To explore this hypothesis, we performed a meta-analysis on studies that examined DUR in CHR-P individuals in relation to their clinical outcomes. This review was conducted in accordance with the PRISMA guidelines and the protocol was registered with PROSPERO on 16th April 2021 (ID no. CRD42021249443). Literature searches were conducted using PsycINFO and Web of Science in March and November 2021, for studies reporting on DUR in CHR-P populations, in relation to transition to psychosis or symptomatic, functional, or cognitive outcomes. The primary outcome was transition to psychosis, while the secondary outcomes were remission from CHR-P status and functioning at baseline. Thirteen independent studies relating to 2506 CHR-P individuals were included in the meta-analysis. The mean age was 19.88 years (SD = 1.61) and 1194 individuals (47.65 %) were females. The mean length of DUR was 23.61 months (SD = 13.18). There was no meta-analytic effect of DUR on transition to psychosis at 12-month follow-up (OR = 1.000, 95%CI = 0.999-1.000, k = 8, p = .98), while DUR was related to remission (Hedge's g = 0.236, 95%CI = 0.014-0.458, k = 4, p = .037). DUR was not related to baseline GAF scores (beta = -0.004, 95%CI = -0.025-0.017, k = 3, p = .71). The current findings suggest that DUR is not associated with transition to psychosis at 12 months, but may impact remission. However, the database was small and further research in this area is required.

Quality of ADL task performance in persons with schizophrenia: Looking beyond independence

BACKGROUND

Persons with schizophrenia may experience decreased ability to perform activities of daily living (ADL) indicated by need for assistance in everyday life. Others are independent, but their quality of ADL task performance in terms of effort and efficiency may still be impacted.

AIMS/OBJECTIVES

The overall purpose of this study was to explore the quality of ADL task performance in subgroups with schizophrenia (independent/needing assistance).

MATERIALS AND METHODS

Participants were in- and outpatients at a Psychiatric Hospital diagnosed with schizophrenia (n = 83). Their quality of ADL task performance was evaluated using the Assessment of Motor and Process Skills (AMPS). Evaluations were conducted at the hospital. Two subgroups (A: independent and B: needing assistance) were created based on AMPS ADL ability measures.

RESULTS

The majority in both subgroups had AMPS ADL ability measures within the risk zones. Further, the majority in subgroup A had ADL ability measures within age expectations but below mean for well persons of the same age. Both ineffective motor and process skills were identified in both subgroups.

CONCLUSIONS/SIGNIFICANCE

Occupational therapy is indicated for persons with schizophrenia, both for independent persons and for persons needing assistance. This is to prevent decline in or to enhance ADL ability.

A meta-analysis of ultra-high field glutamate, glutamine, GABA and glutathione 1HMRS in psychosis: Implications for studies of psychosis risk

Ultra-high field proton magnetic resonance spectroscopy (1HMRS) offers a unique opportunity to measure the concentration of neurometabolites implicated in psychosis (PSY). The extant 7 T 1HMRS literature measuring glutamate-associated neurometabolites in the brain in PSY in vivo is small, but a comprehensive, quantitative summary of these data can offer insight and guidance to this emerging field. This meta-analysis examines proton spectroscopy (1HMRS) measures of glutamate (Glu), glutamine (Gln), glutamate+glutamine (Glx), gamma aminobutyric acid (GABA), and glutathione (GSH) across 255 individuals with PSY (121 first episode) and 293 healthy comparison participants (HC). While all five neurometabolites were lower in PSY as compared to HC, only Glu (Cohen's d = -0.18) and GSH (Cohen's d = -0.21) concentrations were significantly lower in PSY, whereas concentrations of Gln, Glx, and GABA did not significantly differ between groups. Notably, 1HMRS methodological choices and sample demographic characteristics did not impact study-specific effect sizes for PSY-related Glu or GSH differences. This review thus provides further evidence of neurometabolite dysfunction in first episode and chronic PSY, and thereby suggests that Glu and GSH abnormalities may additionally play a role in more incipient stages of the disorder: in clinical high risk stages. Additional 7 T neurochemical imaging studies in larger, longitudinal, and unmedicated samples and in youth at risk for developing psychosis are needed. Such studies will be critical for elucidating the neurodevelopmental and clinical time course of PSY-related neurometabolite alterations, and for assessing the potential for implicated metabolites to serve as druggable targets for decreasing PSY risk.

Resveratrol Adjunct Therapy for Negative Symptoms in Patients With Stable Schizophrenia: A Double-Blind, Randomized Placebo-Controlled Trial

BACKGROUND

Patients with schizophrenia can generally manifest a broad variety of primary negative symptoms. The current study aimed to assess the efficacy and tolerability of resveratrol add-on therapy in the treatment of negative symptoms in patients with stable schizophrenia.

METHODS

In a randomized, double-blind, and placebo-controlled setting, schizophrenia patients were assigned to receive either 200 mg/d resveratrol or matched placebo in addition to a stable dose of risperidone for 8 weeks. Patients were assessed using the positive and negative syndrome scale, the extrapyramidal symptom rating scale, and Hamilton Depression Rating Scale over the trial period. The primary outcome was considered as the change in positive and negative subscale score from baseline to week 8 between the treatment arms.

RESULTS

A total 52 patients completed the trial (26 in each arm). Baseline characteristics of both groups were statistically similar (P  > .05). Despite the statistically similar behavior of positive symptoms between the groups across time (Greenhouse-Geisser corrected: F = 1.76, df = 1.88, P = .180), the resveratrol group demonstrated greater improvement in negative, general psychopathology, and total scores (Greenhouse-Geisser corrected: F = 12.25, df = 2.04, P < .001; F = 5.42, df = 1.56, P = .011; F = 7.64, df = 1.48, P = .003). HDRS scores and its changes, ESRS score, and frequency of other complications were not significantly different between resveratrol and placebo groups.

CONCLUSION

Adding resveratrol to risperidone can exhibit remarkable efficacy and safety in terms of management of schizophrenia-related negative symptoms.

Ascorbic acid improves extrapyramidal syndromes and corpus striatal degeneration induced by dopamine-2 receptor inhibition in Wistar rats

Objectives The prolonged uses of fourth-generation antipsychotics have been implicated in inducing extrapyramidal syndromes characterized by the motor deficit. This was attributed to the loss of dopamine-2 receptor (D2R) signaling. However, ascorbic acid (SVCT2R stimulation) in the brain is proposed to modulate D2R activity. We, therefore, investigated the beneficial roles of ascorbic acid in improving the extrapyramidal symptoms seen in D2R loss. Methods Twenty adult male Wistar rats of average weight 200 g were distributed randomly into four groups. The control (NS) received normal saline for 28 days, Untreated D2R inhibition group (-D2R) received normal saline for seven days and then subsequently received chlorpromazine for 21 days, D2R inhibition group treated with ascorbic acid (-D2R+SVCT2R) received chlorpromazine for 21 days and was subsequently treated with ascorbate for seven days while the withdrawal group (WG) received chlorpromazine for 21 days and subsequently received normal saline for seven days. Motor deficits were assessed using a rotarod and cylinder test. The corpus striatum was harvested, processed, and stained using H&E and Nissl stains. Cellular density was analyzed using Image J software 1.8.0. Results Motor deficit was observed in -D2R animals administered chlorpromazine with less improvement in WG compared to control (p<0.05) in both rotarod and cylinder test. Ascorbic acid (SVCT2R stimulation) significantly (p<0.001) improved the latency of fall and climbing attempts observed in -D2R animals. The density of basophilic trigoid bodies was significantly (p<0.001) restored in -D2R+SVCT2R group, suggesting recovery of neural activity in the corpus striatum. Moreover, the hallmarks of neuronal degeneration were less expressed in the ascorbic acid treatment groups. Conclusions Ascorbic acid putatively ameliorates extrapyramidal symptoms observed in D2R blockage by chlorpromazine in Wistar rats.

The prevalence of psychiatric symptoms before the diagnosis of Parkinson's disease in a nationwide cohort: A comparison to patients with cerebral infarction

Objectives

Psychiatric symptoms (PS) can be non-motor features in Parkinson’s disease (PD) which are common even in the prodromal, untreated phase of the disease. Some PS, especially depression and anxiety recently became known predictive markers for PD. Our objective was to explore retrospectively the prevalence of PS before the diagnosis of PD.

Methods

In the framework of the Hungarian Brain Research Program we created a database from medical and medication reports submitted for reimbursement purposes to the National Health Insurance Fund in Hungary, a country with 10 million inhabitants and a single payer health insurance system. We used record linkage to evaluate the prevalence of PS before the diagnosis of PD and compared that with patients with ischemic cerebrovascular lesion (ICL) in the period between 2004–2016 using ICD-10 codes of G20 for PD, I63-64 for ICL and F00-F99 for PS. We included only those patients who got their PD, ICL and psychiatric diagnosis at least twice.

Results

There were 79 795 patients with PD and 676 874 patients with ICL. Of the PD patients 16% whereas of those with ischemic cerebrovascular lesion 9.7% had a psychiatric diagnosis before the first appearance of PD or ICL (p<0.001) established in psychiatric care at least twice. The higher rate of PS in PD compared to ICL remained significant after controlling for age and gender in logistic regression analysis. The difference between PD and ICL was significant for Mood disorders (F30-F39), Organic, including symptomatic, mental disorders (F00-F09), Neurotic, stress-related and somatoform disorders (F40-F48) and Schizophrenia, schizotypal and delusional disorders (F20-F29) diagnosis categories (p<0.001, for all).

Discussion

The higher rate of psychiatric morbidity in the premotor phase of PD may reflect neurotransmitter changes in the early phase of PD.

Fibroblast Growth Factor: Promising Target for Schizophrenia

Schizophrenia is one of the most debilitating mental disorders around the world. It is characterized by neuroanatomical or biochemical changes. The role of the fibroblast growth factors (FGFs) system in schizophrenia has received considerable attention in recent years. Various changes in the gene expression and/or level of FGFs have been implicated in the etiology, symptoms and progression of schizophrenia. For example, studies have substantiated an interaction between FGFs and the signaling pathway of dopamine receptors. To understand the role of this system in schizophrenia, the databases of Open Access Journals, Web of Science, PubMed (NLM), LISTA (EBSCO), and Google Scholar with keywords including fibroblast growth factors, dopamine, schizophrenia, psychosis, along with neurotrophic were searched. In conclusion, the FGF family represent molecular candidates as new drug targets and treatment targets for schizophrenia.

A Novel Phosphodiesterase 1 Inhibitor DSR-141562 Exhibits Efficacies in Animal Models for Positive, Negative, and Cognitive Symptoms Associated with Schizophrenia

In our drug discovery program, we identified a novel orally available and brain-penetrant phosphodiesterase (PDE) 1 inhibitor, 3-methyl-7-(tetrahydro-2H-pyran-4-yl)-2-{[trans-4-(trifluoromethyl)cyclohexyl]-methoxy}imidazo[5,1-f][1,2,4]triazin-4(3H)-one (DSR-141562). In the present study, we characterized the preclinical profile of DSR-141562. This compound has preferential selectivity for predominantly brain-expressed PDE1B over other PDE1 family members, and high selectivity for the PDE1 family over other PDE families and 65 other tested biologic targets. Oral administration of DSR-141562 at 10 mg/kg slightly elevated the cGMP concentration, and it potently enhanced the increase of cGMP induced by a dopamine D₁ receptor agonist in mouse brains. The cGMP level in monkey cerebrospinal fluid was also elevated after treatment with DSR-141562 at 30 and 100 mg/kg and could be used as a translational biomarker. Since PDE1B is believed to regulate dopaminergic and glutamatergic signal transduction, we evaluated the effects of this compound using schizophrenia-related behavioral assays. DSR-141562 at 3-30 mg/kg potently inhibited methamphetamine-induced locomotor hyperactivity in rats, while it had only minimal effects on the spontaneous locomotor activity. Furthermore, DSR-141562 at 1-100 mg/kg did not induce any signs of catalepsy in rats. DSR-141562 at 0.3-3 mg/kg reversed social interaction and novel object recognition deficits induced by repeated treatment with an N-methyl-D-aspartate receptor antagonist, phencyclidine, in mice and rats, respectively. In common marmosets, DSR-141562 at 3 and 30 mg/kg improved the performance in object retrieval with detour tasks. These results suggest that DSR-141562 is a therapeutic candidate for positive, negative, and cognitive symptoms in schizophrenia. SIGNIFICANCE STATEMENT: This is the first paper showing that a phosphodiesterase 1 inhibitor is efficacious in animal models for positive and negative symptoms associated with schizophrenia. Furthermore, we demonstrated that this compound improved cognitive function in the common marmoset, a nonhuman primate.

Repetitive transcranial magnetic stimulation as an adjunctive treatment for negative symptoms and cognitive impairment in patients with schizophrenia: a randomized, double-blind, sham-controlled trial

Purpose: Effective treatment options for negative symptoms and cognitive impairment in patients with schizophrenia are still to be developed. The present study was to examine potential benefits of repetitive transcranial magnetic stimulation (rTMS) to improve negative symptoms and cognition in this patient population. Methods: The study was a 4-week, randomized, double-blind sham-controlled trial. Patients with schizophrenia were treated with adjunctive 20-Hz rTMS for 4 weeks or sham condition to the left dorsolateral prefrontal cortex (DLPFC). Negative symptoms were measured using the Scale for the Assessment of Negative Symptoms (SANS) and the Positive and Negative symptom scale (PANSS) negative subscale at baseline and week 4. Cognitive function was measured using the MATRICS Consensus Cognitive Battery (MCCB) at the same two time points. In addition, possible moderators for rTMS treatment efficacy were explored. Results: Sixty patients (33 in the treatment group, 27 in the sham group) completed the study. There was a significant decrease in negative symptoms after 4-week rTMS treatment as measured by the SANS total score and the PANSS negative symptom subscale score. However, there was no significant improvement in cognition with rTMS treatment. Stepwise multiple linear regression analysis suggested that the baseline severity of positive symptoms may predict poorer improvement in negative symptoms at week 4. Conclusion: Twenty-Hz rTMS stimulation over left DLPFC as an adjunctive treatment might be beneficial in improving negative symptoms of schizophrenia. Future studies with a longer treatment duration and a larger sample size are needed. Clinical trial ID: NCT01940939.

Synthesis and Biological Evaluation of Fused Tricyclic Heterocycle Piperazine (Piperidine) Derivatives As Potential Multireceptor Atypical Antipsychotics

Herein, a novel series of multireceptor ligands was developed as polypharmacological antipsychotic agents using the designed multiple ligand approach between dopamine receptors and serotonin receptors. Among them, compound 47 possessed unique pharmacological features, exhibiting high affinities for D₂, D₃, 5-HT_1A, 5-HT_2A, and 5-HT₆ receptors and low efficacy at the off-target receptors (5-HT_2C, histamine H₁, and adrenergic α₁ receptor). Compound 47 showed dose-dependent inhibition of apomorphine- and MK-801-induced motor behavior, and the conditioned avoidance response with low cataleptic effect. Moreover, compound 47 resulted nonsignificantly serum prolactin levels and weight gain change compared with risperidone. Additionally, compound 47 possessed a favorable pharmacokinetic profile with oral bioavailability of 58.8% in rats. Furthermore, compound 47 displayed procognition properties in a novel object recognition task in rats. Taken together, compound 47 may constitute a novel class of atypical antipsychotic drugs for schizophrenia.

Glutamate imaging (GluCEST) reveals lower brain GluCEST contrast in patients on the psychosis spectrum

Psychosis commonly develops in adolescence or early adulthood. Youths at clinical high risk (CHR) for psychosis exhibit similar, subtle symptoms to those with schizophrenia (SZ). Malfunctioning neurotransmitter systems, such as glutamate, are implicated in the disease progression of psychosis. Yet, in vivo imaging techniques for measuring glutamate across the cortex are limited. Here, we use a novel 7 Tesla MRI glutamate imaging technique (GluCEST) to estimate changes in glutamate levels across cortical and subcortical regions in young healthy individuals and ones on the psychosis spectrum. Individuals on the psychosis spectrum (PS; n=19) and healthy young individuals (HC; n=17) underwent MRI imaging at 3 and 7 T. At 7 T, a single slice GluCEST technique was used to estimate in vivo glutamate. GluCEST contrast was compared within and across the subcortex, frontal, parietal and occipital lobes. Subcortical (χ2 (1)=4.65, P=0.031) and lobular (χ2 (1)=5.17, P=0.023) GluCEST contrast levels were lower in PS compared with HC. Abnormal GluCEST contrast levels were evident in both CHR (n=14) and SZ (n=5) subjects, and correlated differentially, across regions, with clinical symptoms. Our findings describe a pattern of abnormal brain neurochemistry early in the course of psychosis. Specifically, CHR and young SZ exhibit diffuse abnormalities in GluCEST contrast attributable to a major contribution from glutamate. We suggest that neurochemical profiles of GluCEST contrast across cortex and subcortex may be considered markers of early psychosis. GluCEST methodology thus shows promise to further elucidate the progression of the psychosis disease state.

Dopamine Targeting Drugs for the Treatment of Schizophrenia: Past, Present and Future

Schizophrenia is a chronic and debilitating neuropsychiatric disorder affecting approximately 1% of the world's population. This disease is associated with considerable morbidity placing a major financial burden on society. Antipsychotics have been the mainstay of the pharmacological treatment of schizophrenia for decades. The traditional typical and atypical antipsychotics demonstrate clinical efficacy in treating positive symptoms, such as hallucinations and delusions, while are largely ineffective and may worsen negative symptoms, such as blunted affect and social withdrawal, as well as cognitive function. The inability to treat these latter symptoms may contribute to social function impairment associated with schizophrenia. The dysfunction of multiple neurotransmitter systems in schizophrenia suggests that drugs selectively targeting one neurotransmission pathway are unlikely to meet all the therapeutic needs of this heterogeneous disorder. Often, however, the unintentional engagement of multiple pharmacological targets or even the excessive engagement of intended pharmacological targets can lead to undesired consequences and poor tolerability. In this article, we will review marketed typical and atypical antipsychotics and new therapeutic agents targeting dopamine receptors and other neurotransmitters for the treatment of schizophrenia. Representative typical and atypical antipsychotic drugs and new investigational drug candidates will be systematically reviewed and compared by reviewing structure-activity relationships, pharmacokinetic properties, drug metabolism and safety, pharmacological properties, preclinical data in animal models, clinical outcomes and associated side effects.

Metaphor in psychosis: on the possible convergence of Lacanian theory and neuro-scientific research

Starting from the theories of leading psychiatrists, like Kraepelin and de Clérambault, the French psychoanalyst Jacques Lacan (1901–1981) formulated an original theory of psychosis, focusing on the subject and on the structuring role of language. In particular, he postulated that language makes up the experience of subjectivity and that psychosis is marked by the absence of a crucial metaphorization process. Interestingly, in contemporary psychiatry there is growing empirical evidence that schizophrenia is characterized by abnormal interpretation of verbal and non-verbal information, with a great difficulty to put such information in the appropriate context. Neuro-scientific contributions have investigated this difficulty suggesting the possibility of interpreting schizophrenia as a semiotic disorder which makes the patients incapable of understanding the figurative meaning of the metaphoric speech, probably due to a dysfunction of certain right hemisphere areas, such as the right temporoparietal junction and the right superior/middle temporal gyrus. In this paper we first review the Lacanian theory of psychosis and neuro-scientific research in the field of symbolization and metaphoric speech. Next, we discuss possible convergences between both approaches, exploring how they might join and inspire one another. Clinical and neurophysiological research implications are discussed.

"Domain gauges": A reference system for multivariate profiling of brain fMRI activation patterns induced by psychoactive drugs in rats

Pharmacological magnetic resonance imaging (phMRI) of the brain has become a widely used tool in both preclinical and clinical drug research. One of its challenges is to condense the observed complex drug-induced brain-activation patterns into semantically meaningful metrics that can then serve as a basis for informed decision making. To aid interpretation of spatially distributed activation patterns, we propose here a set of multivariate metrics termed "domain gauges", which have been calibrated based on different classes of marketed or validated reference drugs. Each class represents a particular "domain" of interest, i.e., a specific therapeutic indication or mode of action. The drug class is empirically characterized by the unique activation pattern it evokes in the brain-the "domain profile". A domain gauge provides, for any tested intervention, a "classifier" as a measure of response strength with respect to the domain in question, and a "differentiator" as a measure of deviation from the domain profile, both along with error ranges. Capitalizing on our in-house database with an unprecedented wealth of standardized perfusion-based phMRI data obtained from rats subjected to various validated treatments, we exemplarily focused on 3 domains based on therapeutic indications: an antipsychotic, an antidepressant and an anxiolytic domain. The domain profiles identified as part of the gauge definition process, as well as the outputs of the gauges when applied to both reference and validation data, were evaluated for their reconcilability with prior biological knowledge and for their performance in drug characterization. The domain profiles provided quantitative activation patterns with high biological plausibility. The antipsychotic profile, for instance, comprised key areas (e.g., cingulate cortex, nucleus accumbens, ventral tegmental area, substantia nigra) which are believed to be strongly involved in mediating an antipsychotic effect, and which are in line with network-level dysfunctions observed in schizophrenia. The domain gauges plausibly positioned the vast majority of the pharmacological and even non-pharmacological treatments. The results also suggest the segregation of sub-domains based on, e.g., the mode of action. Upon judicious selection of domains and careful calibration of the gauges, our approach represents a valuable analytical tool for biological interpretation and decision making in drug discovery.

[What criteria for an ideal antipsychotic treatment?]

Antipsychotics are, by definition, drugs to treat all symptomatic dimensions of schizophrenia, even if, following the discovery of chlorpromazine, the effect assessment has been focused on the ability to reduce positive symptoms. Nevertheless, expectations of treatment are no longer limited to only support this one dimension, but integrate the need to treat negative, cognitive and affective symptoms, through long-term modulation of dopamine transmission but also non-dopaminergic pathways. Beyond symptomatic treatment, it is also necessary to have a treatment modifying the evolution course of the disease (disease modifier), acting by a long-term effect on neuropathological and neurochemical abnormalities. The limitation of long-term effect remains the issue of therapeutic observance. Moreover, this concern for efficiency should be at the cost of reduced induction of adverse effects to maximize the benefit/risk ratio. All these dimensions should the components to profile an ideal antipsychotic treatment in 2015.

Regulation of postsynaptic plasticity genes' expression and topography by sustained dopamine perturbation and modulation by acute memantine: relevance to schizophrenia

A relevant role for dopamine-glutamate interaction has been reported in the pathophysiology and treatment of psychoses. Dopamine and glutamate may interact at multiple levels, including the glutamatergic postsynaptic density (PSD), an electron-dense thickening that has gained recent attention as a switchboard of dopamine-glutamate interactions and for its role in synaptic plasticity. Recently, glutamate-based strategies, such as memantine add-on to antipsychotics, have been proposed for refractory symptoms of schizophrenia, e.g. cognitive impairment. Both antipsychotics and memantine regulate PSD transcripts but sparse information is available on memantine's effects under dopamine perturbation. We tested gene expression changes of the Homer1 and PSD-95 PSD proteins in models of sustained dopamine perturbation, i.e. subchronic treatment by: a) GBR-12909, a dopamine receptor indirect agonist; b) haloperidol, a D2R antagonist; c) SCH-23390, a dopamine D1 receptor (D1R) antagonist; and d) SCH-23390+haloperidol. On the last day of treatment, rats were acutely treated with vehicle or memantine. The Homer1a immediate-early gene was significantly induced by haloperidol and by haloperidol+SCH-23390. The gene was not induced by SCH-23390 per se or by GBR-12909. Expression of the constitutive genes Homer1b/c and PSD-95 was less affected by these dopaminergic paradigms. Acute memantine administration significantly increased Homer1a expression by the dopaminergic compounds used herein. Both haloperidol and haloperidol+SCH-23390 shifted Homer1a/Homer1b/c ratio of expression toward Homer1a. This pattern was sharpened by acute memantine. Dopaminergic compounds and acute memantine also differentially affected topographic distribution of gene expression and coordinated expression of Homer1a among cortical-subcortical regions. These results indicate that dopaminergic perturbations may affect glutamatergic signaling in different directions. Memantine may help partially revert dopamine-mediated glutamatergic dysfunctions.

Mapping dopaminergic deficiencies in the substantia nigra/ventral tegmental area in schizophrenia

Previous work from our laboratory showed deficits in tyrosine hydroxylase protein expression within the substantia nigra/ventral tegmental area (SN/VTA) in schizophrenia. However, little is known about the nature and specific location of these deficits within the SN/VTA. The present study had two aims: (1) test if tyrosine hydroxylase deficits could be explained as the result of neuronal loss; (2) assess if deficits in tyrosine hydroxylase are sub-region specific within the SN/VTA, and thus, could affect specific dopaminergic pathways. To achieve these objectives: (1) we obtained estimates of the number of dopaminergic neurons, total number of neurons, and their ratio in matched SN/VTA schizophrenia and control samples; (2) we performed a qualitative assessment in SN/VTA schizophrenia and control matched samples that were processed simultaneously for tyrosine hydroxylase immunohistochemistry. We did not find any significant differences in the total number of neurons, dopaminergic neurons, or their ratio. Our qualitative study of TH expression showed a conspicuous decrease in labeling of neuronal processes and cell bodies within the SN/VTA, which was sub-region specific. Dorsal diencephalic dopaminergic populations of the SN/VTA presented the most conspicuous decrease in TH labeling. These data support the existence of pathway-specific dopaminergic deficits that would affect the dopamine input to the cortex without significant neuronal loss. Interestingly, these findings support earlier reports of decreases in tyrosine hydroxylase labeling in the target areas for this dopaminergic input in the prefrontal and entorhinal cortex. Finally, our findings support that tyrosine hydroxylase deficits could contribute to the hypodopaminergic state observed in cortical areas in schizophrenia.

Negative symptoms of schizophrenia: clinical characteristics, pathophysiological substrates, experimental models and prospects for improved treatment

Schizophrenia is a complex and multifactorial disorder generally diagnosed in young adults at the time of the first psychotic episode of delusions and hallucinations. These positive symptoms can be controlled in most patients by currently-available antipsychotics. Conversely, they are poorly effective against concomitant neurocognitive dysfunction, deficits in social cognition and negative symptoms (NS), which strongly contribute to poor functional outcome. The precise notion of NS has evolved over the past century, with recent studies - underpinned by novel rating methods - suggesting two major sub-domains: "decreased emotional expression", incorporating blunted affect and poverty of speech, and "avolition", which embraces amotivation, asociality and "anhedonia" (inability to anticipate pleasure). Recent studies implicate a dysfunction of frontocortico-temporal networks in the aetiology of NS, together with a disruption of cortico-striatal circuits, though other structures are also involved, like the insular and parietal cortices, amygdala and thalamus. At the cellular level, a disruption of GABAergic-glutamatergic balance, dopaminergic signalling and, possibly, oxytocinergic and cannibinoidergic transmission may be involved. Several agents are currently under clinical investigation for the potentially improved control of NS, including oxytocin itself, N-Methyl-d-Aspartate receptor modulators and minocycline. Further, magnetic-electrical "stimulation" strategies to recruit cortical circuits and "cognitive-behavioural-psychosocial" therapies likewise hold promise. To acquire novel insights into the causes and treatment of NS, experimental study is crucial, and opportunities are emerging for improved genetic, pharmacological and developmental modelling, together with more refined readouts related to deficits in reward, sociality and "expression". The present article comprises an integrative overview of the above issues as a platform for this Special Issue of European Neuropsychopharmacology in which five clinical and five preclinical articles treat individual themes in greater detail. This Volume provides, then, a framework for progress in the understanding - and ultimately control - of the debilitating NS of schizophrenia.

Revisiting the therapeutic effect of rTMS on negative symptoms in schizophrenia: a meta-analysis

This study sought to determine the moderators in the treatment effect of repetitive transcranial magnetic stimulation (rTMS) on negative symptoms in schizophrenia. We performed a meta-analysis of prospective studies on the therapeutic application of rTMS in schizophrenia assessing the effects of both low-frequency and high-frequency rTMS on negative symptoms. Results indicate that rTMS is effective in alleviating negative symptoms in schizophrenia. The effect size was moderate (0.63 and 0.53, respectively). The effect size of rTMS on negative symptoms in sham-controlled trials was 0.80 as measured by the SANS and 0.41 as measured by the PANSS. A longer duration of illness was associated with poorer efficacy of rTMS on negative symptoms. A 10 Hz setting, at least 3 consecutive weeks of treatment, treatment site at the left dorsolateral prefrontal cortex (DLPFC) and a 110% motor threshold (MT) were found to be the best rTMS parameters for the treatment of negative symptoms. The results of our meta-analysis suggest that rTMS is an effective treatment option for negative symptoms in schizophrenia. The moderators of rTMS on negative symptoms included duration of illness, stimulus frequency, duration of illness, position and intensity of treatment as well as the type of outcome measures used.

α2-Adrenoceptors are targets for antipsychotic drugs

RATIONALE

Almost all antipsychotic drugs (APDs), irrespective of whether they belong to the first-generation (e.g. haloperidol) or second-generation (e.g. clozapine), are dopamine D2 receptor antagonists. Second-generation APDs, which differ from first-generation APDs in possessing a lower propensity to induce extrapyramidal side effects, target a variety of monoamine receptors such as serotonin (5-hydroxytryptamine) receptors (e.g. 5-HT1A, 5-HT2A, 5-HT2C, 5-HT6, 5-HT7) and α1- and α2-adrenoceptors in addition to their antagonist effects at D2 receptors.

OBJECTIVE

This short review is focussed on the potential role of α2-adrenoceptors in the antipsychotic therapy.

RESULTS

Schizophrenia is characterised by three categories of symptoms: positive symptoms, negative symptoms and cognitive deficits. α2-Adrenoceptors are classified into three distinct subtypes in mammals, α2A, α2B and α2C. Whereas the α2B-adrenoceptor seems to play only a minor role in the brain, activation of postsynaptic α2A-adrenoceptors in the prefrontal cortex improves cognitive functions. Preclinical models such as D-amphetamine-induced locomotion, the conditioned avoidance response and the pharmacological N-methyl-D-aspartate receptor hypofunction model have shown that α2C-adrenoceptor blockade or the combination of D2 receptor antagonists with idazoxan (α2A/2C-adrenoceptor antagonist) could be useful in schizophrenia. A potential benefit of a treatment combination of first-generation APDs with the α2A/2C-adrenoceptor antagonists idazoxan or mirtazapine was also demonstrated in patients with schizophrenia.

CONCLUSIONS

It is concluded that α2-adrenoceptors may be promising targets in the antipsychotic therapy.

Disrupted action monitoring in recent-onset psychosis patients with schizophrenia and bipolar disorder

Schizophrenia patients experience cognitive control disturbances, manifest in altered neural signatures during action monitoring. It remains unclear whether error- and conflict-monitoring disturbances co-occur, and whether they are observed in recent-onset psychosis patients with schizophrenia or bipolar disorder. We tested electrophysiological measures of action monitoring in these patients. Seventy-three schizophrenia patients (SZ), 26 bipolar disorder type I patients (BP), each within one year of psychosis onset, and 54 healthy control subjects (HC) underwent EEG during Stroop task performance. In the trial-averaged EEG at three midline scalp electrodes, the error-related negativity (ERN), error positivity (Pe) and conflict-related N450 were measured. Compared to HC (1) SZ exhibited an attenuated ERN and N450, and Pe unchanged and (2) BP exhibited an attenuated ERN but normal Pe and N450. Between patient groups, SZ showed an attenuated N450; ERN and Pe were not significantly different. A small (n=10) SZ subgroup that was not receiving antipsychotic medication showed normal ERPs. Altered error- and conflict-monitoring occur together in the first-episode schizophrenia patients, and these measures are comparable in patients with the first-episode bipolar disorder. Antipsychotic medication may be associated with altered measures of error-monitoring in schizophrenia.

Neurocognitive performance stability in a multiplex multigenerational study of schizophrenia

Certain cognitive measures are heritable and differentiate individuals at risk for schizophrenia from unaffected family members and healthy comparison subjects. These deficits in neurocognitive performance in patients with schizophrenia appear stable in the short-term. However, the duration of most, but not all, longitudinal studies is modest and the majority have relied on traditional average performance measures to examine stability. Using a computerized neurocognitive battery (CNB), we assessed mean performance (accuracy and speed) and intra-individual variability (IIV) in a longitudinal study aimed to examine neurocognitive stability in European-American multiplex families with schizophrenia. Thirty-four patients with schizophrenia, 65 unaffected relatives, and 45 healthy comparison subjects completed the same computerized neurocognitive assessment over approximately 5 years. Measures of mean performance showed that patients had stable accuracy performance but were slower in many neurocognitive domains over time as compared with unaffected family members and healthy subjects. Furthermore, patients and family members showed dissociable patterns of change in IIV for speed across cognitive domains: compared with controls, patients showed higher across-task IIV in performance compared with family members, who showed lower across-task IIV. Patients showed an increase in IIV over time, whereas family members showed a decrease. These findings suggest that measures of mean performance and IIV of speed during a CNB may provide useful information about the genetic susceptibility in schizophrenia.

Identifying persistent negative symptoms in first episode psychosis

BACKGROUND

Although persistent negative symptoms (PNS) are known to contribute significantly to poor functional outcome, they remain poorly understood. We examined the heuristic value of various PNS definitions and their respective prevalence in patients with first episode psychosis (FEP). We also contrasted those definitions to the Proxy for the Deficit Syndrome (PDS) to identify deficit syndrome (DS) in the same FEP cohort.

METHODS

One hundred and fifty-eight FEP patients were separated into PNS and non-PNS groups based on ratings from the Scale for Assessment of Negative Symptoms (SANS). PNS was defined in the following ways: 1) having a score of 3 or greater on at least 1 global subscale of the SANS (PNS_1); 2) having a score of 3 or more on at least 2 global subscales of the SANS (PNS_2); and 3) having a score of 3 or more on a combination of specific SANS subscales and items (PNS_H). For all three definitions, symptoms had to be present for a minimum of six consecutive months. Negative symptoms were measured upon entry to the program and subsequently at 1,2,3,6,9 and 12 months. Functional outcome was quantified at first assessment and month 12.

RESULTS

PNS prevalence: PNS_1 (27%); PNS_2 (13.2%); PNS_H (13.2%). The prevalence of DS was found to be 3% when applying the PDS. Regardless of the definition being applied, when compared to non-PNS, patients in the PNS group were shown to have significantly worse functioning at month 12. All three PNS definitions showed similar associations with functional outcome at month 12.

CONCLUSION

Persistent negative symptoms are present in about 27% of FEP patients with both affective and non-affective psychosis. Although there has previously been doubt as to whether PNS represents a separate subdomain of negative symptoms, the current study suggests that PNS may be more applicable to FEP when compared to DS. Although all three PNS definitions were comparable in predicting functional outcome, we suggest that the PNS definition employed is dependent on the clinical or research objective at hand.

Unique and shared roles of the posterior parietal and dorsolateral prefrontal cortex in cognitive functions

The dorsolateral prefrontal cortex (PFC) and posterior parietal cortex (PPC) are two parts of a broader brain network involved in the control of cognitive functions such as working-memory, spatial attention, and decision-making. The two areas share many functional properties and exhibit similar patterns of activation during the execution of mental operations. However, neurophysiological experiments in non-human primates have also documented subtle differences, revealing functional specialization within the fronto-parietal network. These differences include the ability of the PFC to influence memory performance, attention allocation, and motor responses to a greater extent, and to resist interference by distracting stimuli. In recent years, distinct cellular and anatomical differences have been identified, offering insights into how functional specialization is achieved. This article reviews the common functions and functional differences between the PFC and PPC, and their underlying mechanisms.

Beyond pharmacotherapy: understanding the links between obesity and chronic mental illness

While differences in weight-gain potential exist, both between and within classes of psychiatry medications, most commonly used atypical antipsychotics, mood stabilizers, and antidepressants result in some degree of weight gain. This is not new information and it requires an understanding of the tolerability profiles of different treatments and their goodness of fit with specific patient phenotypes. However, this iatrogenic association represents only a piece of this obesity-mental illness dyad. The complex interplay between psychiatric illness and weight involves neurobiology, psychology, and sociological factors. Parsing the salient variables in people with mental illness is an urgent need insofar as mortality from physical health causes is the most common cause of premature mortality in people with chronic mental illness. Our review examines issues associated with common chronic mental illnesses that may underlie this association and warrant further study if we hope to clinically intervene to control this life-threatening comorbidity.