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Joshi YB. Cholinergic Functioning, Cognition, and Anticholinergic Medication Burden in Schizophrenia. Curr Top Behav Neurosci 2022; 63:393-406. [PMID: 36441495 DOI: 10.1007/7854_2022_400] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Acetylcholine (ACh) signaling is critical for central nervous function and is known to be abnormal in schizophrenia (SZ), a chronic neuropsychiatric disorder in which cognitive deficits persist, despite treatment. This review provides a summary of the clinical evidence linking ACh abnormalities to SZ-associated cognitive deficits, an overview of ACh-based pro-cognitive strategies attempted in SZ, and a survey of recent studies that describe the impact of anticholinergic medication burden on cognitive outcomes in SZ. Methodological challenges that currently limit more substantial investigation of ACh in SZ patients and future directions are also discussed.
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Affiliation(s)
- Yash B Joshi
- Desert Pacific Mental Illness Research Education and Clinical Center, VA San Diego Healthcare System, San Diego, CA, USA.
- Department of Psychiatry, University of California, San Diego, La Jolla, CA, USA.
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Varenicline for cognitive impairment in people with schizophrenia: systematic review and meta-analysis. Psychopharmacology (Berl) 2020; 237:11-19. [PMID: 31792645 DOI: 10.1007/s00213-019-05396-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Accepted: 11/08/2019] [Indexed: 01/09/2023]
Abstract
BACKGROUND People with schizophrenia frequently have cognitive dysfunction, which does not respond to pharmacological interventions. Varenicline has been identified as a potential treatment option for nicotinic receptor dysfunction with a potential to treat cognitive impairment in schizophrenia. METHODS We conducted a systematic review of Pubmed, Embase, Psycinfo, CINAHL and the Cochrane Schizophrenia Trial Registry for randomised controlled trials of varenicline in people with schizophrenia for cognitive dysfunction. We excluded trials among people with dementia. We then undertook a meta-analysis with the primary outcome of difference in change of cognitive measures between varenicline and placebo as well as secondary outcomes of difference in rates of adverse events. We conducted a sensitivity analysis on smoking status and study duration. RESULTS We included four papers in the meta-analysis (n = 339). Varenicline was not superior to placebo for overall cognition (SMD = -0.022, 95% CI -0.154-0.110; Z = -0.333; p = 0.739), attention (SMD = -0.047, 95% CI -0.199-0.104; Z = -0.613; p = 0.540), executive function (SMD = -0.060, 95% CI -0.469-0.348; Z =- 0.290; p = 0.772) or processing speed (SMD = 0.038, 95% CI -0.232-0.308; Z = 0.279; p = 0.780). There was no difference in psychotic symptoms, but varenicline was associated with higher rates of nausea. Sensitivity analyses for smoking status and study duration did not alter the results. CONCLUSION Within the present literature, varenicline does not appear to be a useful target compound for improving cognitive impairment in schizophrenia. Based on these results, a trial would need over 2500 participants to be powered to show statistically significant findings.
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Thompson BM, Barrett ST, Bevins RA. Exploring the interoceptive stimulus effects of nicotine and varenicline. Pharmacol Biochem Behav 2019; 181:9-16. [PMID: 30954637 DOI: 10.1016/j.pbb.2019.04.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Revised: 04/01/2019] [Accepted: 04/02/2019] [Indexed: 02/07/2023]
Abstract
Learning processes associated with nicotine influence the development of addiction to tobacco products. In the present report, we are interested in the interoceptive stimulus effects of nicotine acquiring control over appetitive behaviors - specifically, reward seeking. Also of interest is the current smoking cessation drug, varenicline (Chantix®). Varenicline, with its nicotine-like stimulus effects, can decrease withdrawal and cravings for a subset of individuals addicted to nicotine, though relapse is still common. We trained rats (N = 48) with nicotine (0.4 mg/kg, SC) as an excitatory stimulus (i.e., paired with sucrose) in a drug-discriminated goal-tracking (DGT) task. There was no access to sucrose on interspersed saline days. After acquisition of the initial nicotine-saline discrimination, rats were separated into four groups to test discrimination reversal and drug substitution. The control group maintained nicotine as the excitatory stimulus (NIC+). The substitution group had varenicline (1 mg/kg) replace nicotine as the stimulus paired with sucrose (VAR+). One reversal group had nicotine signal the absence of sucrose (i.e., now available on intermixed saline sessions; NIC-). The last group was similar to the NIC- group except varenicline replaced nicotine on non-reinforced sessions (VAR-). We found that varenicline fully substituted as the training stimulus when the drug-sucrose relation remained in place (VAR+). Both reversal groups acquired the new discrimination, albeit slowly and more variable for the VAR- group in comparison to NIC-. There was an effect of group during substitution testing. Specifically, nicotine fully substituted for varenicline regardless of condition. However, varenicline only partially substituted for the nicotine stimulus. At the start of extinction, responding mimicked that of the rats training condition. However, by extinction session 12, all groups maintained similarly low levels of responding. These findings show nicotine and varenicline share stimulus elements, yet the conclusion of partial to full substitution depends on the nature of the testing protocol.
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Affiliation(s)
- Brady M Thompson
- Department of Psychology, University of Nebraska-Lincoln, Lincoln, NE, USA
| | - Scott T Barrett
- Department of Psychology, University of Nebraska-Lincoln, Lincoln, NE, USA
| | - Rick A Bevins
- Department of Psychology, University of Nebraska-Lincoln, Lincoln, NE, USA.
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The past and future of novel, non-dopamine-2 receptor therapeutics for schizophrenia: A critical and comprehensive review. J Psychiatr Res 2019; 108:57-83. [PMID: 30055853 DOI: 10.1016/j.jpsychires.2018.07.006] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Revised: 06/13/2018] [Accepted: 07/12/2018] [Indexed: 01/28/2023]
Abstract
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.
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Schuster RM, Pachas GN, Stoeckel L, Cather C, Nadal M, Mischoulon D, Schoenfeld DA, Zhang H, Ulysse C, Dodds EB, Sobolewski S, Hudziak V, Hanly A, Fava M, Evins AE. Phase IIb Trial of an α7 Nicotinic Receptor Partial Agonist With and Without Nicotine Patch for Withdrawal-Associated Cognitive Deficits and Tobacco Abstinence. J Clin Psychopharmacol 2018; 38:307-316. [PMID: 29912798 PMCID: PMC6019566 DOI: 10.1097/jcp.0000000000000919] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
PURPOSE/BACKGROUND The objective of this study was to determine whether a novel α7 nicotinic acetylcholine receptor partial agonist improves cognition during nicotine withdrawal and improves abstinence rates. To do so, the effect of the α7 nicotinic acetylcholine receptor partial agonist, encenicline, on cognition and abstinence was evaluated when given as monotherapy and when combined with transdermal nicotine patch (nicotine replacement therapy [NRT]). METHODS Adult daily smokers, n = 160, who were motivated to quit smoking completed cognitive testing at satiated baseline and after overnight abstinence and then were randomized to receive a 12-week trial of encenicline 1 mg twice daily or identical placebo the day of the overnight abstinent cognitive testing. In the first 6 weeks of the 12-week encenicline administration, participants were also randomized to 6 weeks of NRT patch or placebo patch. Primary outcomes were cognition during abstinence and 7-day point-prevalence abstinence at week 12. RESULTS No beneficial effects of encenicline were observed on cognition or abstinence when compared with placebo or when combined with NRT compared with placebo capsule + NRT. Of the 4 conditions, abstinence rates were lowest among those assigned to encenicline alone. CONCLUSIONS Beneficial effects of NRT were observed on cognitive and abstinence outcomes when combined with encenicline compared with encenicline plus placebo patch. Addition of NRT to encenicline improved odds of abstinence approximately 3-fold compared with encenicline plus placebo patch. We conclude that encenicline, 1 mg/d, did not improve abstinence-associated cognitive impairment or abstinence rates as monotherapy or adjunctive therapy to NRT patch.
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Affiliation(s)
| | - Gladys N Pachas
- Department of Psychiatry, Massachusetts General Hospital
- Harvard Medical School
| | - Luke Stoeckel
- Department of Psychiatry, Massachusetts General Hospital
- Harvard Medical School
- Division of Diabetes, Endocrinology, and Metabolic Diseases, National Institute of Diabetes and Digestive and Kidney
Diseases
| | - Corinne Cather
- Department of Psychiatry, Massachusetts General Hospital
- Harvard Medical School
| | - Mireya Nadal
- Department of Psychiatry, Massachusetts General Hospital
- Harvard Medical School
| | - David Mischoulon
- Department of Psychiatry, Massachusetts General Hospital
- Harvard Medical School
| | - David A. Schoenfeld
- Harvard Medical School
- Department of Biostatistics, Massachusetts General Hospital
| | - Haiyue Zhang
- Department of Biostatistics, Massachusetts General Hospital
| | | | | | | | | | - Ailish Hanly
- Department of Psychiatry, Massachusetts General Hospital
| | - Maurizio Fava
- Department of Psychiatry, Massachusetts General Hospital
- Harvard Medical School
| | - A. Eden Evins
- Department of Psychiatry, Massachusetts General Hospital
- Harvard Medical School
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Kozak K, Dermody SS, Rabin RA, Zack M, Barr MS, Tyndale RF, George TP. Effects of varenicline on cognitive function in non-smokers with schizophrenia. Schizophr Res 2018; 197:562-563. [PMID: 28291692 DOI: 10.1016/j.schres.2017.03.023] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Revised: 03/06/2017] [Accepted: 03/07/2017] [Indexed: 11/30/2022]
Affiliation(s)
- Karolina Kozak
- Institute of Medical Sciences (IMS), University of Toronto, Toronto, Ontario, Canada; Addictions Division, Centre for Addiction and Mental Health (CAMH), Toronto, Ontario, Canada.
| | - Sarah S Dermody
- Addictions Division, Centre for Addiction and Mental Health (CAMH), Toronto, Ontario, Canada
| | - Rachel A Rabin
- Institute of Medical Sciences (IMS), University of Toronto, Toronto, Ontario, Canada; Addictions Division, Centre for Addiction and Mental Health (CAMH), Toronto, Ontario, Canada
| | - Martin Zack
- Institute of Medical Sciences (IMS), University of Toronto, Toronto, Ontario, Canada; Molecular Brain Science Department, Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada; Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
| | - Mera S Barr
- Institute of Medical Sciences (IMS), University of Toronto, Toronto, Ontario, Canada; Addictions Division, Centre for Addiction and Mental Health (CAMH), Toronto, Ontario, Canada; Division of Brain and Therapeutics, Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
| | - Rachel F Tyndale
- Division of Brain and Therapeutics, Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada; Molecular Brain Science Department, Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada; Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
| | - Tony P George
- Institute of Medical Sciences (IMS), University of Toronto, Toronto, Ontario, Canada; Addictions Division, Centre for Addiction and Mental Health (CAMH), Toronto, Ontario, Canada; Division of Brain and Therapeutics, Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada; Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
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Designing selective modulators for the nicotinic receptor subtypes: challenges and opportunities. Future Med Chem 2018; 10:433-459. [PMID: 29451400 DOI: 10.4155/fmc-2017-0169] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Nicotinic receptors are membrane proteins involved in several physiological processes. They are considered suitable drug targets for various CNS disorders or conditions, as shown by the large number of compounds which have entered clinical trials. In recent years, nonconventional agonists have been discovered: positive allosteric modulators, allosteric agonists, site-specific agonists and silent desensitizers are compounds able to modulate the receptor interacting at sites different from the orthodox one, or to desensitize the receptor without prior opening. While these new findings can further complicate the pharmacology of these proteins and the design and optimization of ligands, they undoubtedly offer new opportunities to find drugs for the many therapeutic indications involving nicotinic receptors.
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Predictors of tobacco abstinence in outpatient smokers with schizophrenia or bipolar disorder treated with varenicline and cognitive behavioral smoking cessation therapy. Addict Behav 2017; 71:89-95. [PMID: 28285208 DOI: 10.1016/j.addbeh.2017.02.028] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Revised: 02/09/2017] [Accepted: 02/23/2017] [Indexed: 01/13/2023]
Abstract
BACKGROUND The estimated mortality gap between those with and without serious mental illness (SMI) is increasing, now estimated at 28years, which is largely due to smoking-related diseases. AIMS We sought to identify predictors of 14-day continuous abstinence in stable outpatient smokers with SMI. METHOD Adult smokers with schizophrenia spectrum (n=130) or bipolar disorder (n=23) were enrolled in a 12-week course of varenicline and cognitive-behavioral therapy for smoking cessation. RESULTS Independent predictors of abstinence included reduction in withdrawal symptoms prior to the quit day, fewer cigarettes smoked per day at baseline, better baseline attention, remitted alcohol dependence, and lower expectation of peer support to aid quitting. CONCLUSIONS Interventions that consider these targets may improve smoking cessation outcomes in those with SMI.
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Smucny J, Wylie KP, Kronberg E, Legget KT, Tregellas JR. Nicotinic modulation of salience network connectivity and centrality in schizophrenia. J Psychiatr Res 2017; 89:85-96. [PMID: 28193583 PMCID: PMC5373996 DOI: 10.1016/j.jpsychires.2017.01.018] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Revised: 01/09/2017] [Accepted: 01/12/2017] [Indexed: 12/27/2022]
Abstract
Although functional abnormalities of the salience network are associated with schizophrenia, the acute effects of nicotine on its function and network dynamics during the resting state in patients are poorly understood. In this study, the effects of a 7 mg nicotine patch (vs. placebo) on salience network connectivity were examined in 17 patients with schizophrenia and 19 healthy subjects. We hypothesized abnormal connectivity between the salience network and other major networks (e.g. executive network) in patients under placebo administration and amelioration of this difference after nicotine. We also examined effects of nicotine on betweenness centrality (a measure of the influence of a region on information transfer throughout the brain) and local efficiency (a measure of local information transfer) of the network. A hybrid independent component analysis (ICA)/seed-based connectivity approach was implemented in which the salience network was extracted by ICA and cortical network peaks (anterior cingulate cortex (ACC), left and right insula) were used as seeds for whole-brain seed-to-voxel connectivity analysis. Significant drug X diagnosis interactions were observed between the ACC seed and superior parietal lobule and ventrolateral prefrontal cortex. A significant interaction effect was also observed between the left insula seed and middle cingulate cortex. During placebo conditions, abnormal connectivity predicted negative symptom severity and lower global functioning in patients. A significant drug X diagnosis interaction was also observed for betweenness centrality of the ACC. These results suggest that nicotine may target abnormalities in functional connectivity between salience and executive network areas in schizophrenia as well as affect the ability of the salience network to act as an integrator of global signaling in the disorder.
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Affiliation(s)
- Jason Smucny
- Neuroscience Program, University of Colorado Anschutz Medical Campus, Aurora, CO, USA; Department of Psychiatry, University of Colorado Anschutz Medical Campus, Aurora, CO, USA.
| | - Korey P. Wylie
- Department of Psychiatry, University of Colorado Anschutz Medical Campus, Aurora CO USA
| | - Eugene Kronberg
- Department of Psychiatry, University of Colorado Anschutz Medical Campus, Aurora CO USA
| | - Kristina T. Legget
- Neuroscience Program, University of Colorado Anschutz Medical Campus, Aurora CO USA,Research Service, Denver VA Medical Center, Denver, CO USA,Department of Psychiatry, University of Colorado Anschutz Medical Campus, Aurora CO USA
| | - Jason R. Tregellas
- Neuroscience Program, University of Colorado Anschutz Medical Campus, Aurora CO USA,Research Service, Denver VA Medical Center, Denver, CO USA,Department of Psychiatry, University of Colorado Anschutz Medical Campus, Aurora CO USA
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Evins AE, Hoeppner SS, Schoenfeld DA, Hoeppner BB, Cather C, Pachas GN, Cieslak KM, Maravic MC. Maintenance pharmacotherapy normalizes the relapse curve in recently abstinent tobacco smokers with schizophrenia and bipolar disorder. Schizophr Res 2017; 183:124-129. [PMID: 27956009 PMCID: PMC5432398 DOI: 10.1016/j.schres.2016.11.018] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 11/11/2016] [Accepted: 11/12/2016] [Indexed: 11/25/2022]
Abstract
OBJECTIVE To compare the effect of maintenance pharmacotherapy on sustained abstinence rates between recently abstinent smokers with schizophrenia and bipolar disorder (SBD) and general population smokers without psychiatric illness. METHOD We performed a person-level, pooled analysis of two randomized controlled trials of maintenance varenicline, conducted in adult smokers with SBD and general population smokers, controlling for severity of dependence. Smokers abstinent after 12-weeks of open varenicline treatment were randomly assigned to ≥12-weeks maintenance varenicline or identical placebo. RESULTS In those assigned to maintenance placebo, the abstinence rate at week-24 was lower in those with SBD than for those without psychiatric illness (29.4±1.1% vs. 61.8±0.4%, OR:0.26, 95% CI: 0.13, 0.52, p<0.001). In smokers assigned to maintenance pharmacotherapy, however, there was no effect of diagnosis on abstinence rates at week-24 (87.2±0.8% vs. 81.9±0.2%, OR: 1.68, 95% CI: 0.53, 5.32, p=0.38). Time to first lapse was shortest in those with SBD assigned to maintenance placebo (Q1=12days, 95%CI: 4, 16), longer in those without psychiatric illness assigned to maintenance placebo (Q1=17days, 95%CI: 17, 29), still longer in general-population smokers assigned to maintenance varenicline (Q1=88, 95% CI:58,91, and longest in those with SBD who received maintenance varenicline (Q1>95days, 95%CI:non-est), (Χ23df=96.99, p<0.0001; all pairwise comparisons p<0.001). CONCLUSIONS Following a standard 12-week course of pharmacotherapy, people with schizophrenia and bipolar disorder were more likely to relapse to smoking without maintenance varenicline treatment. Maintenance pharmacotherapy could improve longer-term tobacco abstinence rates and reduce known smoking-related health disparities in those with SMI.
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Affiliation(s)
- A. Eden Evins
- Department of Psychiatry, Massachusetts General Hospital and Harvard Medical School, Boston, MA
| | - Susanne S. Hoeppner
- Department of Psychiatry, Massachusetts General Hospital and Harvard Medical School, Boston, MA
| | - David A. Schoenfeld
- Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA
| | - Bettina B. Hoeppner
- Department of Psychiatry, Massachusetts General Hospital and Harvard Medical School, Boston, MA
| | - Corinne Cather
- Department of Psychiatry, Massachusetts General Hospital and Harvard Medical School, Boston, MA
| | - Gladys N. Pachas
- Department of Psychiatry, Massachusetts General Hospital and Harvard Medical School, Boston, MA
| | - Kristina M. Cieslak
- Department of Psychiatry, Massachusetts General Hospital and Harvard Medical School, Boston, MA
| | - Melissa Culhane Maravic
- Department of Psychiatry, Massachusetts General Hospital and Harvard Medical School, Boston, MA
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Lewis AS, van Schalkwyk GI, Bloch MH. Alpha-7 nicotinic agonists for cognitive deficits in neuropsychiatric disorders: A translational meta-analysis of rodent and human studies. Prog Neuropsychopharmacol Biol Psychiatry 2017; 75:45-53. [PMID: 28065843 PMCID: PMC5446073 DOI: 10.1016/j.pnpbp.2017.01.001] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2016] [Revised: 12/24/2016] [Accepted: 01/03/2017] [Indexed: 12/28/2022]
Abstract
Cognitive dysfunction in schizophrenia (SCZ) and Alzheimer's disease (AD) is a major driver of functional disability but is largely unresponsive to current therapeutics. Animal models of cognitive dysfunction relevant to both disorders suggest the α7 nicotinic acetylcholine receptor (nAChR) may be a promising drug development target, with multiple clinical trials subsequently testing this hypothesis in individuals with SCZ and AD. However, the translational value of rodent cognitive tasks for predicting the overall efficacy of this therapeutic target in clinical trials is unknown. To compare effect sizes between rodent and human studies, we searched PubMed and the Cochrane Library for all randomized, placebo-controlled trials of compounds with pharmacological activity at the α7 nAChR for treatment of cognitive dysfunction in SCZ and AD and identified 18 studies comprising 2670 subjects treated with eight different compounds acting as full or partial agonists. Cognitive outcomes were standardized, and random-effects meta-analyses revealed no statistically significant effects of α7 nAChR agonists on overall cognition or any of eight cognitive subdomains when all doses were included (Range of all cognitive outcomes: Cohen's d=-0.077 to 0.12, negative favoring drug). In contrast, analysis of 29 rodent studies testing the same α7 agonists revealed large effect sizes in multiple commonly used preclinical behavioral tests of cognition (Range: d=-1.18 to - 0.73). Our results suggest that targeting the α7 nAChR with agonists is not a robust treatment for cognitive dysfunction in SCZ or AD and necessitate a better understanding of the translational gap for therapeutics targeting the α7 nAChR.
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Affiliation(s)
- Alan S. Lewis
- Department of Psychiatry, Yale University, 34 Park Street, 3rd Floor, Research, New Haven, CT 06508, United States,Corresponding author at: 34 Park Street, 3rd Floor, Research, New Haven, CT 06508, United States. (A.S. Lewis)
| | | | - Michael H. Bloch
- Yale Child Study Center, 230 S. Frontage Road, New Haven, CT 06520, United States
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Effects of varenicline on motor cortical plasticity in non-smokers with schizophrenia. Schizophr Res 2016; 178:50-55. [PMID: 27613505 DOI: 10.1016/j.schres.2016.08.031] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Revised: 08/29/2016] [Accepted: 08/31/2016] [Indexed: 01/13/2023]
Abstract
BACKGROUND Nicotinic acetylcholine receptors (nAChR) have been implicated in the pathophysiology of schizophrenia, and deficits in this system may contribute to high rates of cigarette smoking in this population. nAChR stimulation may modulate neuroplasticity, or long-term potentiation (LTP), which is a key mediator of cognitive performance. Varenicline is a nAChR partial agonist that may improve cognitive deficits in both smokers and non-smokers with schizophrenia; however, the mechanism by which varenicline alters cognition in schizophrenia remains unclear. Thus, the aim of this randomized, double-blind, placebo-controlled, crossover study was to determine the effects of varenicline on LTP-like plasticity indexed through transcranial magnetic stimulation (TMS) in non-smokers with schizophrenia. METHODS Varenicline (0.5mg BID × 5 doses) or placebo was administered to 9 non-smokers with schizophrenia and 10 non-smoker healthy subjects. LTP-like plasticity was induced by TMS and paired associative stimulation (PAS) at 0.1Hz to the left motor cortex and measured every 15min for two hours post-PAS. RESULTS There was a significant diagnosis × medication interaction on peak potentiation (F (3, 34)=6.04, p<0.02) and post-hoc analyses indicated that varenicline significantly increased LTP in schizophrenia and decreased LTP in healthy subjects. CONCLUSIONS These preliminary findings suggest that varenicline may produce differential effects in non-smoking schizophrenia compared to control subjects. Given the role of LTP in learning and memory, these observations may suggest the potential for varenicline in the treatment of cognitive deficits in patients with schizophrenia.
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Nicotinic receptors and lurasidone-mediated reversal of phencyclidine-induced deficit in novel object recognition. Behav Brain Res 2016; 301:204-12. [DOI: 10.1016/j.bbr.2015.10.044] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Revised: 10/16/2015] [Accepted: 10/22/2015] [Indexed: 12/19/2022]
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Smith RC, Amiaz R, Si TM, Maayan L, Jin H, Boules S, Sershen H, Li C, Ren J, Liu Y, Youseff M, Lajtha A, Guidotti A, Weiser M, Davis JM. Varenicline Effects on Smoking, Cognition, and Psychiatric Symptoms in Schizophrenia: A Double-Blind Randomized Trial. PLoS One 2016; 11:e0143490. [PMID: 26730716 PMCID: PMC4701439 DOI: 10.1371/journal.pone.0143490] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Accepted: 11/05/2015] [Indexed: 11/18/2022] Open
Abstract
UNLABELLED Schizophrenic patients have a high rate of smoking and cognitive deficits which may be related to a decreased number or responsiveness of nicotinic receptors in their brains. Varenicline is a partial nicotinic agonist which is effective as an antismoking drug in cigarette smokers, although concerns have been raised about potential psychiatric side-effects. We conducted a double-blind placebo controlled study in 87 schizophrenic smokers to evaluate the effects of varenicline (2 mg/day) on measures of smoking, cognition, psychiatric symptoms, and side-effects in schizophrenic patients who were cigarette smokers. Varenicline significantly decreased cotinine levels (P<0.001), and other objective and subjective measures of smoking (P < .01), and responses on a smoking urges scale (P = .02), more than placebo. Varenicline did not improve scores on a cognitive battery designed to test the effect of drugs on cognitive performance in schizophrenia (the MATRICS battery), either in overall MATRICS battery Composite or individual Domain scores, more than placebo. There were no significant differences between varenicline vs. placebo effects on total symptom scores on psychiatric rating scales, PANSS, SANS, or Calgary Depression scales, and there were no significant drug effects in any of these scales sub-scores when we used Benjamin-Hochberg corrected significance levels (α = .05). Varenicline patients did not show greater side-effects than placebo treated patients at any time point when controlled for baseline side-effect scores. Our study supports the use of varenicline as a safe drug for smoking reduction in schizophrenia but not as a cognitive enhancer. TRIAL REGISTRATION ClinicalTrials.gov 00802919.
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Affiliation(s)
- Robert C. Smith
- Nathan S. Kline Institute for Psychiatric Research, Orangeburg, New York, United States of America
- NYU Langone Medical Center, Department of Psychiatry, New York, New York, United States of America
| | - Revital Amiaz
- Chaim Sheba Medical Center, Ramat-Gan, Israel
- Sackler School of Medicine, Tel Aviv, Israel
| | - Tian-Mei Si
- Peking University Institute of Mental Health, The Key Laboratory for Mental Health, Ministry of Health, Beijing, China
| | - Lawrence Maayan
- Albany Medical Center, Albany, New York, United States of America
| | - Hua Jin
- University of California San Diego, Department of Psychiatry, San Diego, California, United States of America
- VA San Diego Healthcare System, San Diego, California, United States of America
| | - Sylvia Boules
- Nathan S. Kline Institute for Psychiatric Research, Orangeburg, New York, United States of America
| | - Henry Sershen
- Nathan S. Kline Institute for Psychiatric Research, Orangeburg, New York, United States of America
- NYU Langone Medical Center, Department of Psychiatry, New York, New York, United States of America
| | - Chunbo Li
- Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Juanjuan Ren
- Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yanhong Liu
- Peking University Institute of Mental Health, The Key Laboratory for Mental Health, Ministry of Health, Beijing, China
| | - Mary Youseff
- Nathan S. Kline Institute for Psychiatric Research, Orangeburg, New York, United States of America
| | - Abel Lajtha
- Nathan S. Kline Institute for Psychiatric Research, Orangeburg, New York, United States of America
- NYU Langone Medical Center, Department of Psychiatry, New York, New York, United States of America
| | - Alessandro Guidotti
- Psychiatric Institute University of Illinois, Chicago, Illinois, United States of America
| | - Mark Weiser
- Chaim Sheba Medical Center, Ramat-Gan, Israel
- Sackler School of Medicine, Tel Aviv, Israel
| | - John M. Davis
- Psychiatric Institute University of Illinois, Chicago, Illinois, United States of America
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15
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Featherstone RE, Siegel SJ. The Role of Nicotine in Schizophrenia. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2015; 124:23-78. [PMID: 26472525 DOI: 10.1016/bs.irn.2015.07.002] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Schizophrenia is associated with by severe disruptions in thought, cognition, emotion, and behavior. Patients show a marked increase in rates of smoking and nicotine dependence relative to nonaffected individuals, a finding commonly ascribed to the potential ameliorative effects of nicotine on symptom severity and cognitive impairment. Indeed, many studies have demonstrated improvement in patients following the administration of nicotine. Such findings have led to an increased emphasis on the development of therapeutic agents to target the nicotinic system as well as increasing the impetus to understand the genetic basis for nicotinic dysfunction in schizophrenia. The goal of this review article is to provide a critical summary of evidence for the role of the nicotinic system in schizophrenia. The first part will review the role of nicotine in normalization of primary dysfunctions and endophenotypical changes found in schizophrenia. The second part will provide a summary of genetic evidence linking polymorphisms in nicotinic receptor genes to smoking and schizophrenia. The third part will summarize attempts to treat schizophrenia using agents specifically targeting nicotinic and nicotinic receptor subtypes. Although currently available antipsychotic treatments are generally able to manage some aspects of schizophrenia (e.g., positive symptoms) they fail to address several other critically effected aspects of the disease. As such, the search for novel mechanisms to treat this disease is necessary.
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Affiliation(s)
- Robert E Featherstone
- Translational Neuroscience Program, Department of Psychiatry, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
| | - Steven J Siegel
- Translational Neuroscience Program, Department of Psychiatry, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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16
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Lencz T, Malhotra AK. Targeting the schizophrenia genome: a fast track strategy from GWAS to clinic. Mol Psychiatry 2015; 20:820-6. [PMID: 25869805 PMCID: PMC4486648 DOI: 10.1038/mp.2015.28] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2014] [Revised: 01/10/2015] [Accepted: 01/23/2015] [Indexed: 12/23/2022]
Abstract
The Psychiatric Genomics Consortium-Schizophrenia Workgroup (PGC-SCZ) has recently published a genomewide association study (GWAS) identifying >100 genetic loci, encompassing a total of 341 protein-coding genes, attaining genomewide significance for susceptibility to schizophrenia. Given the extremely long time (12-15 years) and expense (>$1 billion) associated with the development of novel drug targets, repurposing of drugs with known and validated targets may be the most expeditious path toward deriving clinical utility from these GWAS findings. In the present study, we examined all genes within loci implicated by the PGC-SCZ GWAS against databases of targets of both approved and registered pharmaceutical compounds. We identified 20 potential schizophrenia susceptibility genes that encode proteins that are the targets of approved drugs. Of these, we prioritized genes/targets that are of clear neuropsychiatric interest and that are also sole members of the linkage disequilibrium block surrounding a PGC-SCZ GWAS hit. In addition to DRD2, 5 genes meet these criteria: CACNA1C, CACNB2, CACNA1I, GRIN2A and HCN1. An additional 20 genes coding for proteins that are the targets of drugs in registered clinical trials, but without approved indications, were also identified. Although considerable work is still required to fully explicate the biological implications of the PGC-SCZ GWAS results, pathways related to these known, druggable targets may represent a promising starting point.
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Affiliation(s)
- T Lencz
- Division of Psychiatry Research, Zucker Hillside Hospital, Glen Oaks, NY, USA,Center for Psychiatric Neuroscience, Feinstein Institute for Medical Research, Manhasset, NY, USA,Departments of Psychiatry and Molecular Medicine, Hofstra University School of Medicine, Hempstead, NY, USA,Division of Psychiatry Research, Zucker Hillside Hospital, 75-59 263rd Street, Glen Oaks, NY 11004, USA. E-mail: or
| | - A K Malhotra
- Division of Psychiatry Research, Zucker Hillside Hospital, Glen Oaks, NY, USA,Center for Psychiatric Neuroscience, Feinstein Institute for Medical Research, Manhasset, NY, USA,Departments of Psychiatry and Molecular Medicine, Hofstra University School of Medicine, Hempstead, NY, USA,Division of Psychiatry Research, Zucker Hillside Hospital, 75-59 263rd Street, Glen Oaks, NY 11004, USA. E-mail: or
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17
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Berg SA, Sentir AM, Bell RL, Engleman EA, Chambers RA. Nicotine effects in adolescence and adulthood on cognition and α₄β₂-nicotinic receptors in the neonatal ventral hippocampal lesion rat model of schizophrenia. Psychopharmacology (Berl) 2015; 232:1681-92. [PMID: 25388292 PMCID: PMC4412763 DOI: 10.1007/s00213-014-3800-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Accepted: 10/31/2014] [Indexed: 11/26/2022]
Abstract
RATIONAL Nicotine use in schizophrenia has traditionally been explained as "self-medication" of cognitive and/or nicotinic acetylcholinergic receptor (nAChR) abnormalities. OBJECTIVES We test this hypothesis in a neurodevelopmental rat model of schizophrenia that shows increased addiction behaviors including enhanced nicotine reinforcement and drug-seeking. METHODS Nicotine transdermal patch (5 mg/kg/day vs. placebo × 10 days in adolescence or adulthood) effects on subsequent radial-arm maze learning (15 sessions) and frontal-cortical-striatal nAChR densities (α4β2; [3H]-epibatidine binding) were examined in neonatal ventral hippocampal lesion (NVHL) and SHAM-operated rats. RESULTS NVHL cognitive deficits were not differentially affected by nicotine history compared to SHAMs. Nicotine history produced minimal cognitive effects while increasing food-reward consumption on the maze, compounding with NVHL-induced overconsumption. Acute nicotine (0.5 mg/kg) delivered before the final maze sessions produced modest improvements in maze performance in rats with nicotine patch histories only, but not differentially so in NVHLs. Consistent with in vivo neuroimaging of β2 nAChR binding in schizophrenia smokers vs. non-smokers and healthy controls, adult NVHLs showed 12% reductions in nAChR binding in MPFC (p < 0.05) but not ventral striatum (<5% changes, p > .40), whereas nicotine history elevated nAChRs across both regions (>30%, p < 0.001) without interacting with NVHLs. Adolescent vs. adult nicotine exposure did not alter nAChRs differentially. CONCLUSIONS Although replicating nicotine-induced upregulation of nAChRs in human smokers and demonstrating NVHL validity in terms of schizophrenia-associated nAChR density patterns, these findings do not support hypotheses explaining increased nicotine use in schizophrenia as reflecting illness-specific effects of nicotine to therapeutically alter cognition or nAChR densities.
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Affiliation(s)
- Sarah A Berg
- Laboratory for Translational Neuroscience of Dual Diagnosis & Development, Suite 314D, 320 West 16th Street, Indianapolis, IN, 46202, USA,
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18
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Bumb JM, Enning F, Leweke FM. Drug repurposing and emerging adjunctive treatments for schizophrenia. Expert Opin Pharmacother 2015; 16:1049-67. [PMID: 25866122 DOI: 10.1517/14656566.2015.1032248] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
INTRODUCTION Schizophrenia is a frequent disorder, which substantially impairs patients' quality of life. Moreover, the burden of illness for patients, their families and for the society, in general, is substantial. Nevertheless, the understanding of the pathophysiology of this syndrome, concise diagnostic methods and more effective and tolerable treatments are still lacking. Thus, innovative approaches and the exploration of new territories are required. AREAS COVERED An overview of repurposed drugs and emerging treatments for schizophrenia is presented, focusing on randomized, controlled trials and meta-analyses. EXPERT OPINION Despite many years of drug research, several needs in the treatment of schizophrenia including the safety and tolerability, stage-dependent and personalized approaches, as well as drug delivery and sustainability have not been addressed sufficiently. Given the current failure of a number of mechanistically new drugs, repurposed compounds may serve as alternative and/or adjunctive agents for schizophrenic patients and for treatment refractory patients in particular. Anti-inflammatory drugs (e.g., acetylsalicylic acid, celecoxib and minocycline), as well as N-acetylcysteine, a precursor of the major antioxidant glutathione, hormones (e.g., estrogen, raloxifene and oxytocin), glutamatergic (e.g., glycine and d-serine) and nicotinergic compounds, 'nutraceuticals' (e.g., ω-3 fatty acids) and cannabidiol, an endocannabinoidmodulator, represent promising agents in this field.
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Affiliation(s)
- Jan Malte Bumb
- Heidelberg University, Central Institute of Mental Health, Department of Psychiatry and Psychotherapy, Medical Faculty Mannheim , J5, 68159 Mannheim , Germany +49 621 1703 2321 ; +49 621 1703 2325 ;
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19
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Rowe AR, Mercer L, Casetti V, Sendt KV, Giaroli G, Shergill SS, Tracy DK. Dementia praecox redux: a systematic review of the nicotinic receptor as a target for cognitive symptoms of schizophrenia. J Psychopharmacol 2015; 29:197-211. [PMID: 25567553 DOI: 10.1177/0269881114564096] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Most individuals with schizophrenia suffer some cognitive dysfunction: such deficits are predictive of longer-term functioning; and current dopamine-blocking antipsychotics have made little impact on this domain. There is a pressing need to develop novel pharmacological agents to tackle this insidious but most disabling of problems. The acetylcholinergic system is involved in cognitive and attentional processing, and its metabotropic and nicotinic receptors are widespread throughout the brain. Deficits in acetylcholinergic functioning occur in schizophrenia, and high rates of tobacco smoking have been posited to represent a form of self-medication. The nicotinic acetylcholine receptor (nAChR) has emerged as a putative target to improve cognitive deficits in schizophrenia, and this study systematically reviewed the emerging data. Nineteen studies were identified, covering three compound classes: agonists at the α7 and α 4β2 nAChRs, and positive allosteric modulators. Overall data are underwhelming: some studies showed significant improvements in cognition but as many studies had negative findings. It remains unclear if this represents drug limitations or nascent study methodology problems. The literature is particularly hindered by variability in inclusion of smokers, generally small sample sizes, and a lack of consensus on cognitive test batteries. Future work should evaluate longer-term outcomes, and, particularly, the effects of concomitant cognitive training.
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Affiliation(s)
- Arann R Rowe
- The Institute of Psychiatry, King's College London, London, UK
| | - Louise Mercer
- The Institute of Psychiatry, King's College London, London, UK
| | - Valentina Casetti
- The Institute of Psychiatry, King's College London, London, UK Oxleas NHS Foundation Trust, London, UK
| | | | | | - Sukhwinder S Shergill
- The Institute of Psychiatry, King's College London, London, UK South London and Maudsley NHS Foundation Trust, London, UK
| | - Derek K Tracy
- The Institute of Psychiatry, King's College London, London, UK Oxleas NHS Foundation Trust, London, UK
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20
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Effective Cessation Strategies for Smokers with Schizophrenia. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2015; 124:133-47. [DOI: 10.1016/bs.irn.2015.08.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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