A randomized exploratory trial of an α-7 nicotinic receptor agonist (TC-5619) for cognitive enhancement in schizophrenia

Nicotine inhalant via E-cigarette facilitates sensorimotor function recovery by upregulating neuronal BDNF-TrkB signalling in traumatic brain injury

BACKGROUND AND PURPOSE

Traumatic brain injury (TBI) causes lifelong physical and psychological dysfunction in affected individuals. The current study investigated the effects of chronic nicotine exposure via E-cigarettes (E-cig) (vaping) on TBI-associated behavioural and biochemical changes.

EXPERIMENTAL APPROACH

Adult C57/BL6J male mice were subjected to controlled cortical impact (CCI) followed by daily exposure to E-cig vapour for 6 weeks. Sensorimotor functions, locomotion, and sociability were subsequently evaluated by nesting, open field, and social approach tests, respectively. Immunoblots were conducted to examine the expression of mature brain-derived neurotrophic factor (mBDNF) and associated downstream proteins (p-Erk, p-Akt). Histological analyses were performed to evaluate neuronal survival and neuroinflammation.

KEY RESULTS

Post-injury chronic nicotine exposure significantly improved nesting performance in CCI mice. Histological analysis revealed increased survival of cortical neurons in the perilesion cortex with chronic nicotine exposure. Immunoblots revealed that chronic nicotine exposure significantly up-regulated mBDNF, p-Erk and p-Akt expression in the perilesion cortex of CCI mice. Immunofluorescence microscopy indicated that elevated mBDNF and p-Akt expression were mainly localized within cortical neurons. Immunolabelling of Iba1 demonstrated that chronic nicotine exposure attenuated microglia-mediated neuroinflammation.

CONCLUSIONS AND IMPLICATIONS

Post-injury chronic nicotine exposure via vaping facilitates recovery of sensorimotor function by upregulating neuroprotective mBDNF/TrkB/Akt/Erk signalling. These findings suggest potential neuroprotective properties of nicotine despite its highly addictive nature. Thus, understanding the multifaceted effects of chronic nicotine exposure on TBI-associated symptoms is crucial for paving the way for informed and properly managed therapeutic interventions.

Characterizing the binding of TC-5619 and encenicline on the alpha7 nicotinic acetylcholine receptor using PET imaging in the pig

The alpha7 nicotinic acetylcholine receptor (α7-nAChR) has has long been considered a promising therapeutic target for addressing cognitive impairments associated with a spectrum of neurological and psychiatric disorders, including Alzheimer's disease and schizophrenia. However, despite this potential, clinical trials employing α7-nAChR (partial) agonists such as TC-5619 and encenicline (EVP-6124) have fallen short in demonstrating sufficient efficacy. We here investigate the target engagement of TC-5619 and encenicline in the pig brain by use of the α7-nAChR radioligand 11C-NS14492 to characterize binding both with in vitro autoradiography and in vivo occupancy using positron emission tomography (PET). In vitro autoradiography demonstrates significant concentration-dependent binding of 11C-NS14492, and both TC-5619 and encenicline can block this binding. Of particular significance, our in vivo investigations demonstrate that TC-5619 achieves substantial α7-nAChR occupancy, effectively blocking approximately 40% of α7-nAChR binding, whereas encenicline exhibits more limited α7-nAChR occupancy. This study underscores the importance of preclinical PET imaging and target engagement analysis in informing clinical trial strategies, including dosing decisions.

Acetylcholine receptor based chemogenetics engineered for neuronal inhibition and seizure control assessed in mice

Epilepsy is a prevalent disorder involving neuronal network hyperexcitability, yet existing therapeutic strategies often fail to provide optimal patient outcomes. Chemogenetic approaches, where exogenous receptors are expressed in defined brain areas and specifically activated by selective agonists, are appealing methods to constrain overactive neuronal activity. We developed BARNI (Bradanicline- and Acetylcholine-activated Receptor for Neuronal Inhibition), an engineered channel comprised of the α7 nicotinic acetylcholine receptor ligand-binding domain coupled to an α1 glycine receptor anion pore domain. Here we demonstrate that BARNI activation by the clinical stage α7 nicotinic acetylcholine receptor-selective agonist bradanicline effectively suppressed targeted neuronal activity, and controlled both acute and chronic seizures in male mice. Our results provide evidence for the use of an inhibitory acetylcholine-based engineered channel activatable by both exogenous and endogenous agonists as a potential therapeutic approach to treating epilepsy.

Role of Alpha-7-Nicotinic Acetylcholine Receptor in Alzheimer's Disease

Alzheimer's disease (AD) is a neurodegenerative disorder affecting millions worldwide. One of the leading hypotheses for the underlying cause of AD is a reduction in nicotinic receptor levels in the brain. Among the nicotinic receptors, the alpha-7-nicotinic acetylcholine receptor (α7nAChR) has received particular attention due to its involvement in cognitive function.α7nAChR is a ligand-gated ion channel that is primarily found in the hippocampus and prefrontal cortex, areas of the brain responsible for learning, memory, and attention. Studies have shown that α7nAChR dysfunction is a key contributor to the pathogenesis of AD. The receptor is involved in regulating amyloidbeta (Aβ) production, a hallmark of AD pathology. Many drugs have been investigated as α7nAChR agonists or allosteric modulators to improve cognitive deficits in AD. Clinical studies have shown promising results with α7nAChR agonists, including improved memory and cognitive function. Although several studies have shown the significance of the α7 nAChR in AD, little is known about its function in AD pathogenesis. As a result, in this review, we have outlined the basic information of the α7 nAChR's structure, functions, cellular responses to its activation, and its role in AD's pathogenesis.

A Multi-task Platform for Profiling Cognitive and Motivational Constructs in Humans and Nonhuman Primates

Background

Understanding the neurobiological substrates of psychiatric disorders requires comprehensive evaluations of cognitive and motivational functions in preclinical research settings. The translational validity of such evaluations will be supported by (1) tasks with high construct validity that are engaging and easy to teach to human and nonhuman participants, (2) software that enables efficient switching between multiple tasks in single sessions, (3) software that supports tasks across a broad range of physical experimental setups, and (4) by platform architectures that are easily extendable and customizable to encourage future optimization and development.

New Method

We describe the Multi-task Universal Suite for Experiments ( M-USE ), a software platform designed to meet these requirements. It leverages the Unity video game engine and C# programming language to (1) support immersive and engaging tasks for humans and nonhuman primates, (2) allow experimenters or participants to switch between multiple tasks within-session, (3) generate builds that function across computers, tablets, and websites, and (4) is freely available online with documentation and tutorials for users and developers. M-USE includes a task library with seven pre-existing tasks assessing cognitive and motivational constructs of perception, attention, working memory, cognitive flexibility, motivational and affective self-control, relational long-term memory, and visuo-spatial problem solving.

Results

M-USE was used to test NHPs on up to six tasks per session, all available as part of the Task Library, and to extract performance metrics for all major cognitive and motivational constructs spanning the Research Domain Criteria (RDoC) of the National Institutes of Mental Health.

Comparison with Existing Methods

Other experiment design and control systems exist, but do not provide the full range of features available in M-USE, including a pre-existing task library for cross-species assessments; the ability to switch seamlessly between tasks in individual sessions; cross-platform build capabilities; license-free availability; and its leveraging of video-engine capabilities used to gamify tasks.

Conclusions

The new multi-task platform facilitates cross-species translational research for understanding the neurobiological substrates of higher cognitive and motivational functions.

Low-dose lithium adjunct to quetiapine improves cognitive task performance in mice with MK801-induced long-term cognitive impairment: Evidence from a pilot study

BACKGROUND

Low-dose lithium (LD-Li) has been shown to rescue cognitive impairment in mouse models of short-term mild cognitive impairment, dementia, and schizophrenia. However, few studies have characterized the effects of LD-Li, alone or in conjunction with anti-psychotics, in the mouse model of MK801-induced long term cognitive impairment.

METHODS

The present study used in vivo Ca2+ imaging and a battery of cognitive function assessments to investigate the long-term effects of LD-Li on cognition in mice exposed to repeated injections of MK801. Prefrontal Ca2+ activity was visualized to estimate alterations in neural activity in the model mice. Pre-pulse inhibition (PPI), novel object recognition (NOR), Morris water maze (MWM), and fear conditioning (FC) tasks were used to characterize cognitive performance; open field activity (OFA) testing was used to observe psychotic symptoms. Two treatment strategies were tested: LD-Li [250 mg/d human equivalent dose (HED)] adjunct to quetiapine (QTP; 600 mg/d HED); and QTP-monotherapy (mt; 600 mg/d HED).

RESULTS

Compared to the QTP-mt group, the LD-Li + QTP group showed greatly improved cognitive performance on all measures between experimental days 29 and 85. QTP-mt improved behavioral measures compared to untreated controls, but the effects persisted only from day 29 to day 43. These data suggest that LD-Li + QTP is superior to QTP-mt for improving long-term cognitive impairments in the MK801 mouse model.

LIMITATIONS

There is no medical consensus regarding lithium use in patients with schizophrenia.

CONCLUSION

More pre-clinical and clinical studies are needed to further investigate effective treatment strategies for patients with long-term cognitive impairments, such as chronic schizophrenia.

Imaging Cholinergic Receptors in the Brain by Positron Emission Tomography

Cholinergic receptors represent a promising class of diagnostic and therapeutic targets due to their significant involvement in cognitive decline associated with neurological disorders and neurodegenerative diseases as well as cardiovascular impairment. Positron emission tomography (PET) is a noninvasive molecular imaging tool that has helped to shed light on the roles these receptors play in disease development and their diverse functions throughout the central nervous system (CNS). In recent years, there has been a notable advancement in the development of PET probes targeting cholinergic receptors. The purpose of this review is to provide a comprehensive overview of the recent progress in the development of these PET probes for cholinergic receptors with a specific focus on ligand structure, radiochemistry, and pharmacology as well as in vivo performance and applications in neuroimaging. The review covers the structural design, pharmacological properties, radiosynthesis approaches, and preclinical and clinical evaluations of current state-of-the-art PET probes for cholinergic receptors.

Side Groups Convert the α7 Nicotinic Receptor Agonist Ether Quinuclidine into a Type I Positive Allosteric Modulator

The quinuclidine scaffold has been extensively used for the development of nicotinic acetylcholine receptor (nAChR) agonists, with hydrophobic substituents at position 3 of the quinuclidine framework providing selectivity for α7 nAChRs. In this study, six new ligands (4-9) containing a 3-(pyridin-3-yloxy)quinuclidine moiety (ether quinuclidine) were synthesized to gain a better understanding of the structural-functional properties of ether quinuclidines. To evaluate the pharmacological activity of these ligands, two-electrode voltage-clamp and single-channel recordings were performed. Only ligand 4 activated α7 nAChR. Ligands 5 and 7 had no effects on α7 nAChR, but ligands 6, 8, and 9 potentiated the currents evoked by ACh. Ligand 6 was the most potent and efficacious of the potentiating ligands, with an estimated EC50 for potentiation of 12.6 ± 3.32 μM and a maximal potentiation of EC20 ACh responses of 850 ± 120%. Ligand 6 increased the maximal ACh responses without changing the kinetics of the current responses. At the single-channel level, the potentiation exerted by ligand 6 was evidenced in the low micromolar concentration range by the appearance of prolonged bursts of channel openings. Furthermore, computational studies revealed the preference of ligand 6 for an intersubunit site in the transmembrane domain and highlighted some putative key interactions that explain the different profiles of the synthesized ligands. Notably, Met276 in the 15' position of the transmembrane domain 2 almost abolished the effects of ligand 6 when mutated to Leu. We conclude that ligand 6 is a novel type I positive allosteric modulator (PAM-I) of α7 nAChR.

A selective literature review exploring the role of the nicotinic system in schizophrenia

Nicotine use is more prevalent in patients with psychiatric disorders, especially those diagnosed with psychotic illnesses. Previously, this higher prevalence has been partially attributed to the potential ameliorative effects of nicotine on symptom severity and cognitive impairment. Some healthcare professionals and patients perceive there is a beneficial effect of nicotine on mental health. Emerging data show that the harm associated with nicotine in the population of patients with mental health conditions outweighs any potential benefit. This paper will review the evidence surrounding the nicotinic system and schizophrenia, with a focus on any causality between nicotine and psychosis.

Physiologic Functions and Therapeutic Applications of α7 Nicotinic Acetylcholine Receptor in Brain Disorders

Accumulating data suggest that α7 nicotinic acetylcholine receptors (α7nAChRs) are an important therapeutic target for the treatment of Alzheimer's disease (AD) and schizophrenia. The homopentameric ligand-gated ion channel α7nAChR consists of five identical α7 subunits that are encoded by the CHRNA7 (cholinergic receptor nicotinic alpha7 subunit) gene. Moreover, α7nAChRs are densely distributed throughout the hippocampus, cortex, and thalamus brain regions, but sparsely in the striatum, forebrain, and medulla. Compared with other nAChRs, α7nAChR binds with low affinity to the naturally occurring neurotransmitter acetylcholine and the non-specific exogenous agonist nicotine, and with high affinity to the specific antagonists α-bungarotoxin and methyllycaconitine. Reports indicate that α7nAChR plays important roles in neurotransmitter release, cognitive functioning, and the cholinergic anti-inflammatory response. Genetic variations that alter CHRNA7 mRNA and protein expression or cause α7nAChR dysfunction are associated with many brain disorders. Our previous studies revealed that α7nAChR exerts neuroprotection in AD by acting as a cargo receptor for binding the autophagosomal marker protein LC3 and engulfing extracellular neurotoxic Aβ_1-42 during autophagic degradation of the α7nAChR-Aβ_1-42 complex. However, the role of α7nAChRs in other diseases remains unknown. Here, we review and summarize the essential characteristics and current findings concerning α7nAChRs in four common brain diseases (AD, Parkinson's disease, schizophrenia, and depression), which may elucidate the role of α7nAChRs and inform innovative research and novel treatments that target α7nAChRs in brain disease.

Substance use, microbiome and psychiatric disorders

Accumulating evidence from several studies has shown association between substance use, dysregulation of the microbiome and psychiatric disorders such as depression, anxiety, and psychosis. Many of the abused substances such as cocaine and alcohol have been shown to alter immune signaling pathways and cause inflammation in both the periphery and the central nervous system (CNS). In addition, these substances of abuse also alter the composition and function of the gut microbiome which is known to play important roles such as the synthesis of neurotransmitters and metabolites, that affect the CNS homeostasis and consequent behavioral outcomes. The emerging interactions between substance use, microbiome and CNS neurochemical alterations could contribute to the development of psychiatric disorders. This review provides an overview of the associative effects of substance use such as alcohol, cocaine, methamphetamine, nicotine and opioids on the gut microbiome and psychiatric disorders involving anxiety, depression and psychosis. Understanding the relationship between substance use, microbiome and psychiatric disorders will provide insights for potential therapeutic targets, aimed at mitigating these adverse outcomes.

Evidence for Alpha7 Nicotinic Receptor Activation During the Cough Suppressing Effects Induced by Nicotine and Identification of ATA-101 as a Potential Novel Therapy for the Treatment of Chronic Cough

Studies performed in healthy smokers have documented a diminished responsiveness to tussive challenges, and several lines of experimental evidence implicate nicotine as an antitussive component in both cigarette smoke and the vapors generated by electronic cigarettes (eCigs). We set out to identify the nicotinic receptor subtype involved in the antitussive actions of nicotine and to further evaluate the potential of nicotinic receptor-selective agonists as cough-suppressing therapeutics. We confirmed an antitussive effect of nicotine in guinea pigs. We additionally observed that the alpha-4 beta-2 (α ₄ β ₂)-selective agonist Tc-6683 was without effect on evoked cough responses in guinea pigs, while the α ₇-selective agonist PHA 543613 dose-dependently inhibited evoked coughing. We subsequently describe the preclinical evidence in support of ATA-101, a potent and highly selective (α ₇) selective nicotinic receptor agonist, as a potential candidate for antitussive therapy in humans. ATA-101, formerly known as Tc-5619, was orally bioavailable and moderately central nervous system (CNS) penetrant and dose-dependently inhibited coughing in guinea pigs evoked by citric acid and bradykinin. Comparing the effects of airway targeted administration versus systemic dosing and the effects of repeated dosing at various times prior to tussive challenge, our data suggest that the antitussive actions of ATA-101 require continued engagement of α ₇ nicotinic receptors, likely in the CNS. Collectively, the data provide the preclinical rationale for α ₇ nicotinic receptor engagement as a novel therapeutic strategy for cough suppression. The data also suggest that α ₇ nicotinic acetylcholine receptor (nAChR) activation by nicotine may be permissive to nicotine delivery in a way that may promote addiction. SIGNIFICANCE STATEMENT: This study documents the antitussive actions of nicotine and identifies the α₇ nicotinic receptor subtype as the target for nicotine during cough suppression described in humans. We additionally present evidence suggesting that ATA-101 and other α₇ nicotinic receptor-selective agonists may be promising candidates for the treatment of chronic refractory cough.

Nicotinic Acetylcholine Receptors in the Respiratory Tract

Nicotinic acetylcholine receptors (nAChR) are widely distributed in neuronal and non-neuronal tissues, where they play diverse physiological roles. In this review, we highlight the recent findings regarding the role of nAChR in the respiratory tract with a special focus on the involvement of nAChR in the regulation of multiple processes in health and disease. We discuss the role of nAChR in mucociliary clearance, inflammation, and infection and in airway diseases such as asthma, chronic obstructive pulmonary disease, and cancer. The subtype diversity of nAChR enables differential regulation, making them a suitable pharmaceutical target in many diseases. The stimulation of the α3β4 nAChR could be beneficial in diseases accompanied by impaired mucociliary clearance, and the anti-inflammatory effect due to an α7 nAChR stimulation could alleviate symptoms in diseases with chronic inflammation such as chronic obstructive pulmonary disease and asthma, while the inhibition of the α5 nAChR could potentially be applied in non-small cell lung cancer treatment. However, while clinical studies targeting nAChR in the airways are still lacking, we suggest that more detailed research into this topic and possible pharmaceutical applications could represent a valuable tool to alleviate the symptoms of diverse airway diseases.

[An effect of cholinesterase blockade on negative symptoms in schizophrenia]

Abstruct.

OBJECTIVE

To assess the possibilities of influencing the severity of negative disorders in schizophrenic patients with cholinesterase blockade.

MATERIAL AND METHODS

The study included stable 26 patients (13 of them women), average age 40.4 (SD 11.7) with paranoid schizophrenia, episodic form according to ICD-10). All patients received antipsychotic therapy, which was not changed at least for 2 months. We used psychometric scales (Positive and Negative Syndrome Assessment Scale (PANSS), Global Functioning Scale (GAF), neurocognitive techniques (Brief Assessment of Cognition in Schizophrenia-BACS), projective psychological techniques (Rorschach test).

RESULTS AND CONCLUSION

The results of the study showed that augmentation of maintenance antipsychotic therapy with a cholinesterase blocker (ipidacrine at a dose of 20 mg per day) had positive impact on negative symptoms, decreasing the severity of emotional deficiency. The positive changes of cognitive impairment, measured with BACS, occurred regardless of changes in the severity of negative disorders, measured with PANSS. The Rorschach test showed an improvement in the conventional orientation of the patients' thinking. No exacerbation of psychotic symptoms was registered.

Cognitive Enhancers in Schizophrenia: A Systematic Review and Meta-Analysis of Alpha-7 Nicotinic Acetylcholine Receptor Agonists for Cognitive Deficits and Negative Symptoms

Background: Schizophrenia is a severe and enduring disease and is one of the leading causes of disability worldwide. Cognitive impairment is a core clinical symptom that plays a crucial role in functional outcomes and prognosis, thus making it a relevant treatment target. The aim of this study was to assess the efficacy of alpha-7 nicotinic acetylcholine receptor agonists (α7 nAChR) as adjunctive treatment to enhance cognition and ameliorate negative symptoms in patients with schizophrenia. Methods: A search strategy was developed for MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials up to May 2019. We included randomized controlled trials (RCTs) that compared antipsychotic treatment plus α7 nAChR agonists with antipsychotic treatment plus placebo and determined their effects on the main cognitive domains proposed by the MATRICS initiative and on negative symptoms. Two authors independently reviewed study eligibility and data extraction and assessed the risk of bias of the studies included. According to the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) framework, we used a random-effects model and assessed the quality of the evidence. Results: Thirteen studies were included in the quantitative analysis. No differences were found in any of the cognitive domains assessed in four RCTs (n = 414). In contrast, nine RCTs (n = 978) presented a small effect in support of α7 nAChR agonists for negative symptoms [standardized mean difference -0.28, 95% CI (-0.56 to -0.00); P = 0.05], even though the confidence to support this evidence is low according to the GRADE system. Conclusions: Current evidence is too weak to consider α7 nAChR agonists as an effective add-on treatment to antipsychotics to enhance cognition and negative symptoms.

Alpha7 nicotinic-N-methyl-D-aspartate hypothesis in the treatment of schizophrenia and beyond

Development of novel treatments for positive, cognitive, and negative symptoms continue to be a high-priority area of schizophrenia research and a major unmet clinical need. Given that all randomized controlled trials (RCTs) conducted to date failed with one add-on medication/mechanism of action, future RCTs with the same approach are not warranted. Even if the field develops a medication for cognition, others are still needed to treat negative and positive symptoms. Therefore, fixing one domain does not completely solve the problem. Also, targeting the cholinergic system, glutamatergic system, and cholinergic plus alpha7 nicotinic and N-methyl-D-aspartate (NMDA) receptors failed independently. Hence, targeting other less important pathophysiological mechanisms/targets is unlikely to be successful. Meta-analyses of RCTs targeting major pathophysiological mechanisms have found some efficacy signal in schizophrenia; thus, combination treatments with different mechanisms of action may enhance the efficacy signal. The objective of this article is to highlight the importance of conducting RCTs with novel combination treatments in schizophrenia to develop antischizophrenia treatments. Positive RCTs with novel combination treatments that target the alpha7 nicotinic and NMDA receptors simultaneously may lead to a disease-modifying therapeutic armamentarium in schizophrenia. Novel combination treatments that concurrently improve the three domains of psychopathology and several prognostic and theranostic biomarkers may facilitate therapeutic discovery in schizophrenia.

Cough Remedies for Children and Adolescents: Current and Future Perspectives

Cough is a widespread symptom in children and adolescents. Despite advances in scientific knowledge about the neurophysiological mechanisms underlying the cough reflex, the best therapeutic approaches for children and adolescents who cough remain unclear, and many needs are still unmet. Many remedies for cough are self-prescribed, reflecting strong demand, but significant evidence of their efficacy and safety is missing in pediatric populations. Moreover, as most coughs are part of self-limited illnesses, treatment could be considered unnecessary in some patients. Drug therapy to relieve cough and other symptoms is an essential part of treating a child with cough. However, unfortunately, the number of studies in each category of cough medications is minimal, and dosing and treatment duration varies significantly among studies. Some treatments have been shown to be no more effective than placebo. Lack of clear indications for dosing and treatment duration, the number of available drugs, the numerous active ingredients in products, and multiple caregivers administering medication to children have been considered contributors to an increased risk of inappropriate prescribing, accidental overdosing, and adverse events. This review presents the most recent evidence on the safety and efficacy of available cough remedies, focusing on the pediatric age group, and includes H₁ receptor antagonists, mucolytics and expectorants, drugs acting peripherally on the cough reflex, drugs acting centrally on the cough reflex, drugs acting both peripherally and centrally on the cough reflex, and other compounds, including menthol, glycerol, honey, and medical devices composed of complex natural substances. Future perspectives on new therapeutic targets are also discussed.

Association of cigarette smoking with cognitive impairment in male patients with chronic schizophrenia

BACKGROUND

Previous studies have shown that patients with schizophrenia have higher smoking rates and worse cognitive function than healthy controls. However, there is no consistent conclusion about the relationship between smoking and cognitive impairment.

OBJECTIVES

The main purpose of this study was to explore the effects of smoking on cognitive function by using MATRICS Cognitive Consensus Battery (MCCB) in Chinese male patients with schizophrenia.

METHODS

There were 164 patients with chronic schizophrenia and 82 healthy controls. All subjects were interviewed about smoking status. The cognitive function was assessed by MCCB and Stroop tests. The Positive and Negative Syndrome Scale (PANSS) was used to assess the clinical symptoms of the patients.

RESULTS

Compared with healthy controls, patients had lower MCCB scores in all of its domain scores (all p < 0.05). In the patients, the scores of spatial span test (42.3 ± 11.6), digital sequence test (42.9 ± 10.6), and Hopkins Verbal Learning Test (42.2 ± 10.1) were lower in smokers than those in nonsmokers (all p < 0.05, effect size: 0.28-0.45). Logistic regression analysis showed that the smoking status of the patients was correlated with digital sequence score (p < 0.05, OR = 1.072, 95%CI: 1.013-1.134). Multivariate regression analysis showed that the spatial span total score (β = - 0.26, t = - 2.74, p < 0.001) was associated with the duration of smoking in patients with schizophrenia.

CONCLUSIONS

Our findings show that smoking patients with chronic schizophrenia exhibit more severe cognitive impairment than nonsmoking patients, especially in working memory and executive function.

Meta-analysis of randomized controlled trials of galantamine in schizophrenia: significant cognitive enhancement

Cognitive impairments are core features of schizophrenia and the best predictor of functional outcome. Cholinergic system and alpha-7 nicotinic acetylcholine (α7nACh) receptors are strongly implicated in the pathophysiologic mechanisms associated with cognitive impairments in schizophrenia. Galantamine is not only a reversible, competitive inhibitor of acetylcholinesterase but also a type I positive allosteric modulator of α7nACh receptors. The objective of this meta-analysis was to examine the efficacy of galantamine for cognitive symptoms of schizophrenia. In the meta-analysis that included six randomized controlled trials (RCTs, N=226), cognitive impairments significantly improved with galantamine compared to placebo, with a small Hedges' g effect size of 0.233. This finding is consistent with other RCTs in schizophrenia with medications with a similar mechanism of action. On the basis of the results from all the failed (although some efficacy has been shown) RCTs to date in schizophrenia, targeting only one pathophysiologic mechanism may be insufficient to detect a clinically meaningful signal. Nicotinergic medications, like any other add-on medications, are unlikely to be effective as stand-alone medications. Hence, these medications may have to be combined with other medications with complementary mechanisms such as glutamatergic/N-methyl-D-aspartate systems to detect a meaningful effect size for the three domains of psychopathology.

Double blind, two dose, randomized, placebo-controlled, cross-over clinical trial of the positive allosteric modulator at the alpha7 nicotinic cholinergic receptor AVL-3288 in schizophrenia patients

Despite their theoretical rationale, nicotinic alpha-7 acetylcholine (nα₇) receptor agonists, have largely failed to demonstrate efficacy in placebo-controlled trials in schizophrenia. AVL-3288 is a nα₇ positive allosteric modulator (PAM), which is only active in the presence of the endogenous ligand (acetylcholine), and thus theoretically less likely to cause receptor desensitization. We evaluated the efficacy of AVL-3288 in a Phase 1b, randomized, double-blind, placebo-controlled, triple cross-over study. Twenty-four non-smoking, medicated, outpatients with schizophrenia or schizoaffective disorder and a Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) ≥62 were randomized. Each subject received 5 days of AVL-3288 (10, 30 mg) and placebo across three separate treatment weeks. The primary outcome measure was the RBANS total scale score, with auditory P50 evoked potential suppression the key target engagement biomarker. Secondary outcome measures include task-based fMRI (RISE task), mismatch negativity, the Scale for the Assessment of Negative Symptoms of Schizophrenia (SANS) and the Brief Psychiatric Rating Scale (BPRS). Twenty-four subjects were randomized and treated without any clinically significant treatment emergent adverse effects. Baseline RBANS (82 ± 17) and BPRS (41 ± 13) scores were consistent with moderate impairment. Primary outcomes were negative, with non-significant worsening for both active groups vs. placebo in the P50 and minimal between group changes on the RBANS. In conclusion, the results did not indicate efficacy of the compound, consistent with most prior results for the nα₇ target.

Alpha 7 nicotinic receptor agonist and positive allosteric modulators improved social and molecular deficits of MK-801 model of schizophrenia in rats

Schizophrenia is a common psychiatric disease that cannot be fully treated with current antipsychotic drugs. It has shown that glutamatergic NMDA receptor antagonists such as MK-801 cause schizophrenia-like phenotype in rodents. Recent studies indicated that α7 nicotinic acetylcholine receptor (nAChR) deficits contribute to schizophrenia. Enhancing its activity with agonist or positive allosteric modulators (PAMs) may be a valuable approach for treatment. The certain intracellular pathways such as Akt/Glycogen synthase kinase 3 beta (GSK-3β) and phosphodiesterase-4 (PDE-4)/cAMP are associated with the pathogenesis of schizophrenia. In this study, we examined the effect of α7 nAChR agonists and PAMs on the behavioral and molecular phenotype of schizophrenia in the subchronic MK-801 administered rats. Social interaction, the levels of α7 nAChR, and related intracellular pathways (cAMP, PDE4A, PDE4D, p-Akt/Akt, p-GSK-3β/GSK-3β) were measured by behavioral or ELISA and western blot tests. Subchronic MK-801 administration decreased the following behaviors and increased the avoiding behaviors. However, only α7 nAChR agonist (A-582941) increased the following behavior while α7 nAChR agonist, PAMs (CCMI and PNU-120596), and clozapine decreased the avoiding behavior compared to MK-801. For molecular parameters, MK-801 administration decreased the α7 nAChR, p-Akt/Akt, p-GSK-3β/GSK-3β expressions, and cAMP levels while it increased PDE4A, PDE4D expressions in the prefrontal cortex. Besides, MK-801 decreased the α7 nAChR, p-GSK-3β/GSK-3β expressions in the hippocampus. We found clozapine, α7 nAChR agonists, and PAMs reversed the molecular deficits induced by MK-801. Herein, we showed that prefrontal cortex is more sensitive to the devastating effects of subchronic MK-801 administration, especially for PDE4, in rats. In addition to clozapine, α7 nAChR agonists and PAMs found to be beneficial on both social and molecular deficits induced by MK-801 in rats. We suggested that α7 nAChR agonists and PAMs might be valuable approaches to treat negative symptoms of schizophrenia when unmet needs and current limitations considered in this pathology.

α7 nicotinic acetylcholine receptors as therapeutic targets in schizophrenia: Update on animal and clinical studies and strategies for the future

Schizophrenia is a devastating mental illness and its effective treatment is among the most challenging issues in psychiatry. The symptoms of schizophrenia are heterogeneous ranging from positive symptoms (e.g., delusions, hallucinations) to negative symptoms (e.g., anhedonia, social withdrawal) to cognitive dysfunction. Antipsychotics are effective at ameliorating positive symptoms in some patients; however, they are not reliably effective at improving the negative symptoms or cognitive impairments. The inability to address the cognitive impairments is a particular concern since they have the greatest long-term impact on functional outcomes. While decades of research have been devoted to the development of pro-cognitive agents for schizophrenia, to date, no drug has been approved for clinical use. Converging behavioral, neurobiological, and genetic evidence led to the identification of the α7-nicotinic acetylcholine receptor (α7-nAChR) as a therapeutic target several years ago and there is now extensive preclinical evidence that α7-nAChR ligands have pro-cognitive effects and other properties that should be beneficial to schizophrenia patients. However, like the other pro-cognitive strategies, no α7-nAChR ligand has been approved for clinical use in schizophrenia thus far. In this review, several topics are discussed that may impact the success of α7-nAChR ligands as pro-cognitive agents for schizophrenia including the translational value of the animal models used, clinical trial design limitations, confounding effects of polypharmacy, dose-effect relationships, and chronic versus intermittent dosing considerations. Determining the most optimal pharmacologic strategy at α7-nAChRs: agonist, positive allosteric modulator, or potentially even receptor antagonist is also discussed. article is part of the special issue on 'Contemporary Advances in Nicotine Neuropharmacology'.

Activators of α7 nAChR as Potential Therapeutics for Cognitive Impairment

The α7 nicotinic acetylcholine receptor (nAChR) is a promising target for the treatment of cognitive deficits associated with psychiatric and neurological disorders, including schizophrenia and Alzheimer's disease (AD). Several α7 nAChR agonists and positive allosteric modulators (PAMs) have demonstrated procognitive effects in preclinical models and early clinical trials. However, despite intense research efforts in the pharmaceutical industry and academia, none of the α7 nAChR ligands has been approved for clinical use. This chapter will focus on the α7 nAChR ligands that have advanced to clinical studies and explore the reasons why these agents have not met with unequivocal clinical success.

Evidence-based guidelines for the pharmacological treatment of schizophrenia: Updated recommendations from the British Association for Psychopharmacology

These updated guidelines from the British Association for Psychopharmacology replace the original version published in 2011. They address the scope and targets of pharmacological treatment for schizophrenia. A consensus meeting was held in 2017, involving experts in schizophrenia and its treatment. They were asked to review key areas and consider the strength of the evidence on the risk-benefit balance of pharmacological interventions and the clinical implications, with an emphasis on meta-analyses, systematic reviews and randomised controlled trials where available, plus updates on current clinical practice. The guidelines cover the pharmacological management and treatment of schizophrenia across the various stages of the illness, including first-episode, relapse prevention, and illness that has proved refractory to standard treatment. It is hoped that the practice recommendations presented will support clinical decision making for practitioners, serve as a source of information for patients and carers, and inform quality improvement.

Alpha7 Nicotinic Receptors as Therapeutic Targets in Schizophrenia

While current treatments for schizophrenia often provide much relief for positive symptoms such as hallucinations, other symptoms, particularly cognitive deficits, persist and contribute to substantial suffering and reduced quality of life for patients. In searching for novel therapeutic avenues to treat cognitive deficits in schizophrenia, recent work is exploring nicotinic receptor neurobiology. Supported by a large body of evidence, with contributions from studies of smoking behaviors, genetics, receptor distribution and function, animal models and nicotinic effects on illness symptoms, the alpha7 nicotinic receptor has emerged as a potential therapeutic target. Despite promise in early clinical trials, however, no drug targeting nicotinic systems has succeeded in larger phase 3 trials. Following a brief review of nicotinic receptor biology and the evidence that has led to pursuit of alpha7 nicotinic agonism as a therapeutic strategy, this review will provide an update on the status of recent trials, discuss potential issues that may have contributed to negative outcomes, and point to new directions and promising advances in developing alpha7 nicotinic receptor-based treatment for cognitive symptoms in schizophrenia.

IMPLICATIONS

By examining alpha7 nicotinic receptor biology and recent efforts to target the receptor in clinical trials, it is hoped that investigators will be motivated to explore novel, promising directions focusing on the receptor as a strategy to treat cognitive symptoms in schizophrenia.

Discovery and Development of Non-Dopaminergic Agents for the Treatment of Schizophrenia: Overview of the Preclinical and Early Clinical Studies

Schizophrenia is a chronic psychiatric disorder that affects about 1 in 100 people around the world and results in persistent emotional and cognitive impairments. Untreated schizophrenia leads to deterioration in quality of life and premature death. Although the clinical efficacy of dopamine D2 receptor antagonists against positive symptoms of schizophrenia supports the dopamine hypothesis of the disease, the resistance of negative and cognitive symptoms to these drugs implicates other systems in its pathophysiology. Many studies suggest that abnormalities in glutamate homeostasis may contribute to all three groups of schizophrenia symptoms. Scientific considerations also include disorders of gamma-aminobutyric acid-ergic and serotonergic neurotransmissions as well as the role of the immune system. The purpose of this review is to update the most recent reports on the discovery and development of non-dopaminergic agents that may reduce positive, negative, and cognitive symptoms of schizophrenia, and may be alternative to currently used antipsychotics. This review collects the chemical structures of representative compounds targeting metabotropic glutamate receptor, gamma-aminobutyric acid type A receptor, alpha 7 nicotinic acetylcholine receptor, glycine transporter type 1 and glycogen synthase kinase 3 as well as results of in vitro and in vivo studies indicating their efficacy in schizophrenia. Results of clinical trials assessing the safety and efficacy of the tested compounds have also been presented. Finally, attention has been paid to multifunctional ligands with serotonin receptor affinity or phosphodiesterase inhibitory activity as novel strategies in the search for dedicated medicines for patients with schizophrenia.

Computational Dissociation of Dopaminergic and Cholinergic Effects on Action Selection and Inhibitory Control

BACKGROUND

Patients with schizophrenia make more errors than healthy subjects in the antisaccade task. In this paradigm, participants are required to inhibit a reflexive saccade to a target and to select the correct action (a saccade in the opposite direction). While the precise origin of this deficit is not clear, it has been connected to aberrant dopaminergic and cholinergic neuromodulation.

METHODS

To study the impact of dopamine and acetylcholine on inhibitory control and action selection, we administered two selective drugs (levodopa 200 mg/galantamine 8 mg) to healthy volunteers (N = 100) performing the antisaccade task. The computational model SERIA (stochastic early reaction, inhibition, and late action) was employed to separate the contribution of inhibitory control and action selection to empirical reaction times and error rates.

RESULTS

Modeling suggested that levodopa improved action selection (at the cost of increased reaction times) but did not have a significant effect on inhibitory control. By contrast, according to our model, galantamine affected inhibitory control in a dose-dependent fashion, reducing inhibition failures at low doses and increasing them at higher levels. These effects were sufficiently specific that the computational analysis allowed for identifying the drug administered to an individual with 70% accuracy.

CONCLUSIONS

Our results do not support the hypothesis that elevated tonic dopamine strongly impairs inhibitory control. Rather, levodopa improved the ability to select correct actions. However, inhibitory control was modulated by cholinergic drugs. This approach may provide a starting point for future computational assays that differentiate neuromodulatory abnormalities in heterogeneous diseases like schizophrenia.

Alpha7 nicotinic acetylcholine receptors and neural network synaptic transmission in human induced pluripotent stem cell-derived neurons

The α7 nicotinic acetylcholine receptor has been extensively researched as a target for treatment of cognitive impairment in Alzheimer's disease and schizophrenia. Investigation of the α7 receptor is commonly performed in animals but it is critical to increase the biologically relevance of the model systems to fully capture the physiological role of the α7 receptor in humans. For example most humans, in contrast to animals, express the hybrid gene CHRFAM7A, the product of which modulates α7 receptor activity. In the present study, we used human induced pluripotent stem cell (hiPSC) derived neurons to establish a humanized α7 model. We established a cryobank of neural stem cells (NSCs) that could reproducibly be matured into neurons expressing neuronal markers and CHRNA7 and CHRFAM7A. The neurons responded to NMDA, GABA, and acetylcholine and exhibited synchronized spontaneous calcium oscillations. Gene expression studies and application of a range of α7 positive allosteric modulators (PNU-120595, TQS, JNJ-39393406 and AF58801) together with the α7 agonist PNU-282987 during measurement of intracellular calcium levels demonstrated the presence of functional α7 receptors in matured hiPSC-derived neuronal cultures. Pharmacological α7 activation also resulted in intracellular signaling as measured by ERK 1/2 phosphorylation and c-Fos protein expression. Moreover, PNU-120596 increased the frequency of the spontaneous calcium oscillations demonstrating implication of α7 receptors in human synaptic networks activity. Overall, we show that hiPSC derived neurons are an advanced in vitro model for studying human α7 receptor pharmacology and the involvement of this receptor in cellular processes as intracellular signaling and synaptic transmission.

Discovery of fused heterocyclic carboxamide derivatives as novel α7-nAChR agonists: Synthesis, preliminary SAR and biological evaluation

The α7 nicotinic acetylcholine receptor (α7 nAChR) has emerged as a promising therapeutic target for schizophrenia. In our previous work, a novel series of α7-nAChR agonists bearing scaffold of indolizine were discovered. To explore the effect of aromaticity on the activity and find more active agents, herein, fused heterocyclic carboxamide derivatives were designed and synthesized in this study. Based on the evaluation by two-electrode voltage clamp in Xenopus oocytes, 27 of the synthesized compounds showed obvious agonism of α7 nAChR. Particularly, compounds 10a and 10e showed significantly higher E_max than EVP-6124. The result illustrated the importance of aromaticity to the activity of agonism. Compound 10a, which showed EC₅₀ of 1.88 μM and E_max of 72.4%, was further characterized comprehensively, including co-application with type II positive allosteric modulator PNU-120596, selectivity with other closely related ligand-gated ion channel, etc. The results showed that 10a showed moderate selectivity over other subtypes such as α4β2 and α3β4 nAChR. 10a evoked α7-like currents that were inhibited by MLA and enhanced in the presence of the α7 PAM PNU-120596. The analysis of binding mode and understanding of structure-activity relationship provided insights to develop more potent novel α7-nAChR agonists.

Perioperative activation of spinal α7 nAChR promotes recovery from preoperative stress-induced prolongation of postsurgical pain

Preoperative stress could delay the recovery of postoperative pain and has been reported to be a risk factor for chronic postsurgical pain. As stress could facilitate the proinflammatory activation of microglia, we hypothesized that these cells may play a vital role in the development of preoperative stress-induced pain chronification after surgery. Our experiments were conducted in a rat model that consists of a single prolonged stress (SPS) procedure and plantar incision. A previous SPS exposure induced anxiety-like behaviors, prolonged incision-induced mechanical allodynia, and potentiated the activation of spinal microglia. Based on the results from ex vivo experiments, spinal microglia isolated from SPS-exposed rats secreted more proinflammatory cytokines upon challenge with LPS. Our results also demonstrated that microglia played a more important role than astrocytes in the initiation of SPS-induced prolongation of postsurgical pain. We further explored the therapeutic potential of agonism of α7 nAChR, an emerging anti-inflammatory target, for SPS-induced prolongation of postsurgical pain. Multiple intrathecal (i.t.) injections of PHA-543613 (an α7 nAChR agonist) or PNU-120596 (a type II positive allosteric modulator) during the perioperative period shortened the duration of postsurgical pain after SPS and suppressed SPS-potentiated microglia activation, but their effects were abolished by pretreatment with methyllycaconitine (an α7 nAChR antagonist; i.t.). Based on the results from ex vivo experiments, the anti-inflammatory effects of PHA-543613 and PNU-120596 may have been achieved by the direct modulation of microglia. In conclusion, stress-induced priming of spinal microglia played a key role in the initiation of preoperative stress-induced prolongation of postsurgical pain, and PHA-543613 and PNU-120596 may be potential candidates for preventing pain chronification after surgery.

The relationship between nicotine and psychosis

Cigarette smoking is strongly associated with psychotic disorders such as schizophrenia. For several decades it was assumed that the relationship could be explained by reverse causation; that smoking was secondary to the illness itself, either through self-medication or a process of institutionalization, or was entirely explained by confounding by cannabis use or social factors. However, studies have exposed that such hypotheses cannot fully explain the association, and more recently a bidirectional relationship has been proposed wherein cigarette smoking may be causally related to risk of psychosis, possibly via a shared genetic liability to smoking and psychosis. We review the evidence for these candidate explanations, using findings from the latest epidemiological, neuroimaging, genetic and preclinical work.

Improving cognitive training for schizophrenia using neuroplasticity enhancers: Lessons from decades of basic and clinical research

Mounting evidence indicates that schizophrenia is a disorder that stems from maladaptive plasticity within neural circuits and produces broad cognitive deficits leading to loss of autonomy. A large number of studies have identified abnormalities spanning many neurotransmitter systems in schizophrenia, and as a result, a variety of drugs have been developed to attempt to treat these abnormalities and enhance cognition. Unfortunately, positive results have been limited so far. This may be in part because the scope of abnormalities in the schizophrenic brain requires a treatment capable of engaging many different neurotransmitter systems. One approach to achieving this kind of treatment has been to use neuroplasticity-based computerized cognitive training programs to stimulate the formation of more adaptive circuits. Although the number of studies implementing this approach has increased exponentially in recent years, effect sizes for cognitive gains have been modest and adherence to treatment remains an important challenge in many studies, as patients are often required to train for 40 h or more. In the present paper, we argue that cognitive training protocols will benefit from the addition of cognitive enhancers to produce more robust and longer lasting targeted neuroplasticity. Indeed, recent data from animal studies have provided support for combining plasticity-enhancing drugs with tailored behavioral training paradigms to restore normal function within dysfunctioning neural circuits. The advantages and challenges of applying this approach to patients with schizophrenia will be discussed.

N-methyl-d-aspartate-type glutamate receptor modulators and related medications for the enhancement of auditory system plasticity in schizophrenia

Deficits in N-methyl-d-aspartate-type (NMDAR) function contribute to cognitive deficits in schizophrenia, particularly dysfunction in neuroplasticity, defined as reduced learning during training on exercises that place implicit, increasing demands on early sensory (auditory and visual) information processing. Auditory mismatch negativity (MMN) can be both a target engagement biomarker for the NMDAR and a proxy measure of neurophysiological plasticity. This review covers the evidence for using NMDAR modulator and related compounds for enhancement of cognition, with a particular focus on early auditory processing/plasticity. Compounds covered include glycine site agonists, glycine and system A-type transporter inhibitors, d-amino acid oxidase inhibitors, memantine and nicotinic alpha-7 acetylcholine receptor agonists. As opposed to daily treatment studies focusing on schizophrenia in general, intermittent, non-daily treatment combining NMDAR modulators with neuroplasticity-based paradigms, using MMN as target-engagement biomarkers show promise as treatments to both remediate plasticity deficits and overall functional deficits.

Drug Discovery on Natural Products: From Ion Channels to nAChRs, from Nature to Libraries, from Analytics to Assays

Natural extracts are complex mixtures that may be rich in useful bioactive compounds and therefore are attractive sources for new leads in drug discovery. This review describes drug discovery from natural products and in explaining this process puts the focus on ion-channel drug discovery. In particular, the identification of bioactives from natural products targeting nicotinic acetylcholine receptors (nAChRs) and serotonin type 3 receptors (5-HT3Rs) is discussed. The review is divided into three parts: "Targets," "Sources," and "Approaches." The "Targets" part will discuss the importance of ion-channel drug targets in general, and the α7-nAChR and 5-HT3Rs in particular. The "Sources" part will discuss the relevance for drug discovery of finding bioactive compounds from various natural sources such as venoms and plant extracts. The "Approaches" part will give an overview of classical and new analytical approaches that are used for the identification of new bioactive compounds with the focus on targeting ion channels. In addition, a selected overview is given of traditional venom-based drug discovery approaches and of diverse hyphenated analytical systems used for screening complex bioactive mixtures including venoms.

The past and future of novel, non-dopamine-2 receptor therapeutics for schizophrenia: A critical and comprehensive review

Since the discovery of chlorpromazine in the 1950's, antipsychotic drugs have been the cornerstone of treatment of schizophrenia, and all attenuate dopamine transmission at the dopamine-2 receptor. Drug development for schizophrenia since that time has led to improvements in side effects and tolerability, and limited improvements in efficacy, with the exception of clozapine. However, the reasons for clozapine's greater efficacy remain unclear, despite the great efforts and resources invested therewith. We performed a comprehensive review of the literature to determine the fate of previously tested, non-dopamine-2 receptor experimental treatments. Overall we included 250 studies in the review from the period 1970 to 2017 including treatments with glutamatergic, serotonergic, cholinergic, neuropeptidergic, hormone-based, dopaminergic, metabolic, vitamin/naturopathic, histaminergic, infection/inflammation-based, and miscellaneous mechanisms. Despite there being several promising targets, such as allosteric modulation of the NMDA and α7 nicotinic receptors, we cannot confidently state that any of the mechanistically novel experimental treatments covered in this review are definitely effective for the treatment of schizophrenia and ready for clinical use. We discuss potential reasons for the relative lack of progress in developing non-dopamine-2 receptor treatments for schizophrenia and provide recommendations for future efforts pursuing novel drug development for schizophrenia.

Selective adrenergic alpha2C receptor antagonist ameliorates acute phencyclidine-induced schizophrenia-like social interaction deficits in rats

RATIONALE

Social withdrawal is a core feature of the negative symptoms of schizophrenia. Currently available pharmacotherapies have only limited efficacy towards the negative symptoms, i.e., there is a significant unmet medical need in the treatment of these symptoms.

OBJECTIVE

We wanted to confirm whether selective adrenergic α_2C receptor (AR) antagonist therapy could ameliorate acute phencyclidine (PCP)-induced schizophrenia-like social interaction deficits in rats, and to compare the effects of an α_2C AR antagonist to another putative therapeutic alternative, an α₇ nicotinic acetylcholine receptor (nAChR) partial agonist, as well against three commonly used atypical antipsychotics.

METHODS

Here, we used acute PCP administration and modified a protocol for testing social interaction deficits in male Wistar rats and then used this model to compare the effects of an α_2C AR antagonist (ORM-13070 0.3 and 1.0 mg/kg s.c.) with an α₇ nAChR partial agonist (EVP-6124 0.3 mg/kg s.c.) and three atypical antipsychotics (clozapine 2.5 mg/kg i.p., risperidone 0.04 and 0.08 mg/kg s.c., olanzapine 0.125 and 0.5 mg/kg s.c.) on social interaction behavior.

RESULTS

Acute PCP (1.5 mg/kg s.c.) produced robust and reproducible deficits in social interaction behavior without affecting locomotor activity. The selective α_2C AR antagonist significantly ameliorated PCP-induced social interaction deficits. In contrast, neither the partial α₇ nAChR agonist nor any of the three atypical antipsychotics were able to reverse the behavioral deficits at the selected doses.

CONCLUSION

Our findings confirm that α_2C AR antagonism is a potential mechanism for the treatment of the negative symptoms of schizophrenia.

XII AIST 2018 Conference: “The thousand faces of cough: clinical and therapeutic updates”

This paper summarizes the presentations submitted for publication of the 12^th AIST National Congress (Associazione Italiana Studio Tosse/Italian Association for Cough Study) entitled “The thousand facets of cough. A clinical and therapeutic update”, which occurred last February 2^nd-3^rd, 2018 in Bologna (Italy). It summarizes the contributions from leading experts of the sector, who, as in the previous editions, also this year have analyzed a problem too often underestimated which still has many dark sides as regards both the diagnosis and the therapy of cough. The Scientific Committee has chosen topics that had less space in previous editions and these are topical subjects representing a concrete opportunity for learning and comparison of opinions, as well as indispensable elements for the correct management of the symptoms.

Hereby we report the abstracts of the works submitted for publication in this Meeting report.

The main topics have covered Cough relationship with nerve vagus, ATP, air pollution, GERD, imaging, COPD, pediatric and therapy. Of particular interest it is the preliminary data on cough hydration ratio that shows a highly significant correlation between dehydration and cough.

Potential Role of Antipsychotic-Galantamine-Memantine Combination in the Treatment of Positive, Cognitive, and Negative Symptoms of Schizophrenia

Schizophrenia is, in part, a cognitive illness. There are no approved medications for cognitive impairments associated with schizophrenia (CIAS) and primary negative symptoms. Cholinergic and glutamatergic systems, alpha-7 nicotinic acetylcholine (α-7nACh) and N-methyl-D-aspartate (NMDA) receptors, kynurenic acid (KYNA), and mismatch negativity have been implicated in the pathophysiology of CIAS and negative symptoms. Galantamine is an acetylcholinesterase inhibitor that is also a positive allosteric modulator at the α4β2 and α7nACh receptors. Memantine is a noncompetitive NMDA receptor antagonist. Galantamine and memantine alone and in combination were effective for cognition in animals and people with Alzheimer's disease. The objective of this article is to critically dissect the published randomized controlled trials with galantamine and memantine for CIAS to highlight the efficacy signal. These studies may have failed to detect a clinically meaningful efficacy signal due to limitations, methodological issues, and possible medication nonadherence. There is evidence from a small open-label study that the galantamine-memantine combination may be effective for CIAS with kynurenine pathway metabolites as biomarkers to detect the severity of cognitive impairments. Given that there are no available treatments for cognitive impairments and primary negative symptoms in schizophrenia, testing of this "five-pronged strategy" (quintuple hypotheses: dopamine, nicotinic-cholinergic, glutamatergic/NMDA, GABA, and KYNA) is a "low-risk high-gain" approach that could be a major breakthrough in the field. The galantamine-memantine combination has the potential to treat positive, cognitive, and negative symptoms, and targeting the quintuple hypotheses concurrently may lead to a major scientific advancement - from antipsychotic treatment to antischizophrenia treatment.

Efficacy of different types of cognitive enhancers for patients with schizophrenia: a meta-analysis

Cognitive impairment is a core feature of schizophrenia, which is predictive for functional outcomes and is, therefore, a treatment target in itself. Yet, literature on efficacy of different pharmaco-therapeutic options is inconsistent. This quantitative review provides an overview of studies that investigated potential cognitive enhancers in schizophrenia. We included pharmacological agents, which target different neurotransmitter systems and evaluated their efficacy on overall cognitive functioning and seven separate cognitive domains. In total, 93 studies with 5630 patients were included. Cognitive enhancers, when combined across all different neurotransmitter systems, which act on a large number of different mechanisms, showed a significant (yet small) positive effect size of 0.10 (k = 51, p = 0.023; 95% CI = 0.01 to 0.18) on overall cognition. Cognitive enhancers were not superior to placebo for separate cognitive domains. When analyzing each neurotransmitter system separately, agents acting predominantly on the glutamatergic system showed a small significant effect on overall cognition (k = 29, Hedges’ g = 0.19, p = 0.01), as well as on working memory (k = 20, Hedges’ g = 0.13, p = 0.04). A sub-analysis of cholinesterase inhibitors (ChEI) showed a small effect on working memory (k = 6, Hedges’ g = 0.26, p = 0.03). Other sub-analyses were positively nonsignificant, which may partly be due to the low number of studies we could include per neurotransmitter system. Overall, this meta-analysis showed few favorable effects of cognitive enhancers for patients with schizophrenia, partly due to lack of power. There is a lack of studies involving agents acting on other than glutamatergic and cholinergic systems, especially of those targeting the dopaminergic system.

Citicoline (CDP-choline) add-on therapy to risperidone for treatment of negative symptoms in patients with stable schizophrenia: A double-blind, randomized placebo-controlled trial

OBJECTIVE

We aimed to evaluate the efficacy and tolerability of citicoline add-on therapy in treatment of negative symptoms in patients with stable schizophrenia.

METHODS

In a double-blind and placebo-controlled study, patients with stable schizophrenia (DSM-5) were randomized to receive either 2,500 mg/day citicoline or placebo in addition to risperidone for 8 weeks. The patients were assessed using the positive and negative syndrome scale (PANSS), the extrapyramidal symptom rating scale (ESRS), and Hamilton depression rating scale (HDRS). The primary outcome was the difference in PANSS negative subscale score reduction from baseline to week 8 between the citicoline and the placebo groups.

RESULTS

Sixty-six individuals (out of 73 enrolled) completed the trial. The citicoline group demonstrated significantly greater improvement in negative scores, F(1.840, 118.360) = 8.383, p = .001, as well as general psychopathology, F(1.219, 78.012) = 6.636, p = .008; change in general psychopathology did not remain significant after adjustment, and total PANSS scores, F(1.633, 104.487) = 15.400, p < .001, compared with the placebo. HDRS scores and its changes, ESRS score, and frequency of other side effects were not significantly different between the two groups.

CONCLUSIONS

Citicoline add-on therapy to risperidone can effectively improve the primary negative symptoms of patients with schizophrenia.

Hippocampal α7 nicotinic ACh receptors contribute to modulation of depression-like behaviour in C57BL/6J mice

BACKGROUND AND PURPOSE

Clinical studies have identified links between cholinergic signalling and depression in human subjects. Increased cholinergic signalling in hippocampus also increases behaviours related to anxiety and depression in mice, which can be reversed by ACh receptor antagonists.

EXPERIMENTAL APPROACH

As the α7 subunit of the nicotinic ACh receptor (nAChR) is highly expressed in hippocampus, we determined whether blocking α7 nAChRs could reverse the effects of increased ACh signalling in anxiety- and depression-related behaviours in mice.

KEY RESULTS

Administration of the α7 nAChR agonist GTS-21 had no effect in tail suspension or forced swim tests. Conversely, the α7 nAChR antagonist methyllycaconitine (MLA) induced significant antidepressant-like effects in male mice in these paradigms, consistent with previous studies, but this was not observed in female mice. MLA also decreased physostigmine-induced c-fos immunoreactivity (a marker of neuronal activity) in hippocampus. Local knockdown of α7 nAChRs in hippocampus had no effect on its own but decreased a subset of depression-like phenotypes induced by physostigmine in male mice. Few effects of α7 nAChR knockdown were observed in depression-like behaviors in female mice, possibly due to a limited response to physostigmine. There was no significant effect of hippocampal α7 nAChR knockdown on anxiety-like phenotypes in male mice. However, a modest increase in anxiety-like behavior was observed in female mice infused with a scrambled control vector in response to physostigmine administration, that was not seen after a7 nAChR knockdown in the hippocampus.

CONCLUSIONS AND IMPLICATIONS

These results suggest that ACh signalling through α7 nAChRs in the hippocampus contributes to regulation of a subset of depression-like behaviours when ACh is increased, as can occur under stressful conditions. These studies also provide evidence for sex differences that may be relevant for treatments of mood disorders based on cholinergic signalling.

LINKED ARTICLES

This article is part of a themed section on Nicotinic Acetylcholine Receptors. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.11/issuetoc.

Pharmacokinetic Limitations on Effects of an Alpha7-Nicotinic Receptor Agonist in Schizophrenia: Randomized Trial with an Extended-Release Formulation

The aim of the trial was to assess whether extending plasma levels of the alpha7-nicotinic acetylcholine receptor (nAChR) agonist 3-(2,4-dimethoxybenzylidene)-anabaseine (DMXB-A) over time enhances its cognitive effects in schizophrenia. Both smoking and non-smoking patients were studied, to determine whether effects differ between these two groups. Forty-three smokers and thirty-seven non-smokers who met DSM-IV criteria for schizophrenia were enrolled in a double-blind, randomized, placebo-controlled 1 month trial. DMXB-A 150 mg was formulated with hypromellose to produce extended release over 4 h and administered four times daily. The primary outcome (the Neurocognitive Composite of the MATRICS Consensus Cognitive Battery) and secondary outcomes (the MATRICS Attention-Vigilance Domain and P50 gating), showed no significant effect. Plasma levels were obtained 2.5 h post administration. In non-smokers, levels were similar to those reached transiently with 75-150 mg DMXB-A immediate-release formulations twice daily, which were earlier shown to be effective doses. However, the extended-release formulation produced no cognitive or clinical effect either in non-smokers or smokers. The 10-fold lower DMXB-A plasma levels in smokers suggest that chronic smoking enhances DMXB-A metabolism. Pro-cognitive effects of DMXB-A may result from transient increases in cell signaling that are limited by receptor tachyphylaxis. Future efforts to improve cognition in schizophrenia by enhancing alpha7 nAChR function may require consideration of these pharmacokinetic limitations.

Tobacco smoking and its association with cognition in first episode psychosis patients

Available evidence suggests that nicotine may enhance cognitive functioning. Moreover, it has been suggested that the high prevalence of smoking in people with schizophrenia is in part due to self-medication behaviour to alleviate cognitive deficits. We assessed the association between tobacco smoking and cognitive functioning in a large population of first episode psychosis (FEP) patients (n=304) and healthy controls (n=156). Smokers were not tobacco deprived, or were minimally deprived (≤2h). Verbal memory, visual memory, working memory, processing speed, executive function, motor dexterity and attention were assessed. The smoking prevalence among the FEP group was 57% (n=174). The age at which patients began smoking cigarettes regularly was 16.2years (SD=3.1), an average of 12years before experiencing the first frank symptoms of psychosis (age of onset=28.8; SD=9.3). The number of cigarettes smoked per day was 19.6 (SD=9.4), significantly more than healthy controls [11.0 (SD=7.6); p<0.001]. ANCOVA analysis did not show any significant difference between smokers and non-smokers in in the performance of any of the cognitive tasks in the FEP group or in the healthy control group, independent of gender, age, education or premorbid IQ. This suggests chronic exposure to nicotine through cigarette smoking is not associated with cognitive functioning in first-episode psychosis. These findings do not support the nicotine self-medication hypothesis as a contributor to the high prevalence of smoking among individuals suffering from serious mental illness.

Theoretical study of the binding profile of an allosteric modulator NS-1738 with a chimera structure of the α7 nicotinic acetylcholine receptor

Potentiation of the function of the α7 nicotinic acetylcholine receptor (α7-nAChR) is believed to provide a possible way for the treatment of cholinergic system dysfunctions such as Alzheimer's disease and schizophrenia. Positive allosteric modulators (PAMs) are able to augment the peak current response of the endogenous agonist of α7-nAChR by binding to some allosteric sites. In this study, the binding profile of a potent type I PAM, NS-1738, with a chimera structure (termed α7-AChBP) constructed from the extracellular domain of α7-nAChR and an acetylcholine binding protein was investigated with molecular docking, molecular dynamics simulation, and free energy calculation methods. We found that NS-1738 could bind to three allosteric sites of α7-AChBP, namely, the top pocket, the vestibule pocket and the agonist sub-pocket. NS-1738 has moderate binding affinities (-6.76 to -9.15 kcal mol^-1) at each allosteric site. The urea group is critical for binding and can form hydrogen-bond interactions with the protein. The bulky trifluoromethyl group also has a great impact on the binding modes and binding affinities. We believe that our study provides valuable insight into the binding profiles of type I PAMs with α7-nAChR and is helpful for the development of novel PAMs.

Medications Used for Cognitive Enhancement in Patients With Schizophrenia, Bipolar Disorder, Alzheimer's Disease, and Parkinson's Disease

BACKGROUND/AIMS

Cognitive impairment, which frequently occurs in patients with schizophrenia, bipolar disorder, Alzheimer's disease, and Parkinson's disease, has a significant impact on the daily lives of both patients and their family. Furthermore, since the medications used for cognitive enhancement have limited efficacy, the issue of cognitive enhancement still remains a clinically unsolved challenge.

SAMPLING AND METHODS

We reviewed the clinical studies (published between 2007 and 2017) that focused on the efficacy of medications used for enhancing cognition in patients with schizophrenia, bipolar disorder, Alzheimer's disease, and Parkinson's disease.

RESULTS

Acetylcholinesterase inhibitors and memantine are the standard treatments for Alzheimer's disease and Parkinson's disease. Some studies have reported selective cognitive improvement in patients with schizophrenia following galantamine treatment. Newer antipsychotics, including paliperidone, lurasidone, aripiprazole, ziprasidone, and BL-1020, have also been reported to exert cognitive benefits in patients with schizophrenia. Dopaminergic medications were found to improve language function in patients with Parkinson's disease. However, no beneficial effects on cognitive function were observed with dopamine agonists in patients with schizophrenia. The efficacies of nicotine and its receptor modulators in cognitive improvement remain controversial, with the majority of studies showing that varenicline significantly improved the cognitive function in schizophrenic patients. Several studies have reported that N-methyl-d-aspartate glutamate receptor (NMDAR) enhancers improved the cognitive function in patients with chronic schizophrenia. NMDAR enhancers might also have cognitive benefits in patients with Alzheimer's disease or Parkinson's disease. Raloxifene, a selective estrogen receptor modulator, has also been demonstrated to have beneficial effects on attention, processing speed, and memory in female patients with schizophrenia.

CONCLUSION

Clinical trials with larger sample sizes evaluating comprehensive cognitive domains are warranted to examine the efficacy of medications in cognitive enhancement in patients with schizophrenia, bipolar disorder, Alzheimer's disease, and Parkinson's disease.

Quantification of bowling workload and changes in cognitive function in elite fast bowlers in training compared with Twenty20 Cricket

BACKGROUND

Bowling overs are the primary recorded measure for workloads in cricket for youth through to professionals. However, the validity of this measure has never been tested. Additionally, despite the cognitive component of cricket being suggested to be very high, changes in psychomotor processing speed has again not been explored.

METHODS

Eight professional English county cricket bowlers participated in the study. Participants wore global positioning systems with a tri-axial accelerometer during a Twenty20 match and training. Bowling overs were expressed relative to external forces. Additionally, cognitive function (as measured by psychomotor speed) was assessed pre and post Twenty20 game and training.

RESULTS

When expressed relative to high intensity running distance or external forces from the tri-axial accelerometer, the cost of each over (6 deliveries) was over 100% higher in a Twenty20 game compared to training. Psychomotor speed was unchanged although error within the cognitive task increased post Twenty20 (391±82±547±104 ms) and training (414±110±561±238 ms). This data suggests that reaction time is unchanged from cricket but the chance of making the incorrect decision is increased.

CONCLUSIONS

Movements in fielding should be quantified or bowling workloads adjusted to account for the high intensity fielding associated with Twenty20 cricket. Cognitive function was impaired following bowling, suggesting practitioners may also monitor psychomotor changes when assessing fatigue and allow appropriate time to mentally recover.