Varenicline prevents affective and cognitive exacerbation during smoking abstinence in male patients with schizophrenia

Does nicotine exposure during adolescence modify the course of schizophrenia-like symptoms? Behavioral analysis in a phencyclidine-induced mice model

The first symptoms of schizophrenia (SCHZ) are usually observed during adolescence, a developmental period during which first exposure to psychoactive drugs also occurs. These epidemiological findings point to adolescence as critical for nicotine addiction and SCHZ comorbidity, however it is not clear whether exposure to nicotine during this period has a detrimental impact on the development of SCHZ symptoms since there is a lack of studies that investigate the interactions between these conditions during this period of development. To elucidate the impact of a short course of nicotine exposure across the spectrum of SCHZ-like symptoms, we used a phencyclidine-induced adolescent mice model of SCHZ (2.5mg/Kg, s.c., daily, postnatal day (PN) 38-PN52; 10mg/Kg on PN53), combined with an established model of nicotine minipump infusions (24mg/Kg/day, PN37-44). Behavioral assessment began 4 days after the end of nicotine exposure (PN48) using the following tests: open field to assess the hyperlocomotion phenotype; novel object recognition, a declarative memory task; three-chamber sociability, to verify social interaction and prepulse inhibition, a measure of sensorimotor gating. Phencyclidine exposure evoked deficits in all analyzed behaviors. Nicotine history reduced the magnitude of phencyclidine-evoked hyperlocomotion and impeded the development of locomotor sensitization. It also mitigated the deficient sociability elicited by phencyclidine. In contrast, memory and sensorimotor gating deficits evoked by phencyclidine were neither improved nor worsened by nicotine history. In conclusion, our results show for the first time that nicotine history, restricted to a short period during adolescence, does not worsen SCHZ-like symptoms evoked by a phencyclidine-induced mice model.

Cholinergic Receptors and Addiction

Human behavior can be controlled by physical or psychological dependencies associated with addiction. One of the most insidious addictions in our society is the use of tobacco products which contain nicotine. This addiction can be associated with specific receptors in the brain that respond to the natural neurotransmitter acetylcholine. These nicotinic acetylcholine receptors (nAChR) are ligand-gated ion channels formed by the assembly of one or multiple types of nAChR receptor subunits. In this paper, we review the structure and diversity of nAChR subunits and our understanding for how different nAChR subtypes play specific roles in the phenomenon of nicotine addiction. We focus on receptors containing β2 and/or α6 subunits and the special significance of α5-containing receptors. These subtypes all have roles in regulating dopamine-mediated neurotransmission in the mesolimbic reward pathways of the brain. We also discuss the unique roles of homomeric α7 nAChR in behavioral responses to nicotine and how our knowledge of nAChR functional diversity may help guide pharmacotherapeutic approaches for treating nicotine addiction. While nicotine addiction is a truly global problem, the use of areca nut (betel) products is also a serious addiction associated with public health issues across most of South Asia, impacting as many as 600 million people. We discuss how cholinergic receptors of the brain are also involved with areca addiction and the unique challenges for dealing with addiction to this substance.

Procognitive effects of varenicline in the animal model of schizophrenia depend on α4β2- and α 7-nicotinic acetylcholine receptors

BACKGROUND

Varenicline, a partial agonist of the α4β2 nicotinic acetylcholine receptor (α4β2-nAChR), is currently used to facilitate smoking cessation. Preclinical and clinical studies have suggested that this compound may also be effective in treating cognitive impairments in schizophrenia. However, it is unclear which nicotinic acetylcholine receptor subtypes may be involved because varenicline is not only a partial agonist for α4β2-nAChRs but also a full agonist for α7 nicotinic acetylcholine receptors (α7-nAChRs).

AIM

We investigated the effects of varenicline, compared to the α4β2-nAChR partial agonist TC-2403 and the α7-nAChR full agonist PNU-282987, in a ketamine-based model of schizophrenia-like cognitive deficits on the attentional set-shifting task in rats. The second goal was to elucidate whether the procognitive efficacy of varenicline was due to the compound's action on α4β2-nAChRs or α7-nAChRs.

METHODS

Ketamine was administered to rats for 10 consecutive days and the test was performed 14 days following the last injection. The tested compounds were administered 30 min prior to the attentional set-shifting task.

RESULTS

Varenicline, TC-2403 and PNU-282987 ameliorated ketamine-evoked set-shifting deficits. While the α4β2-nAChR antagonist dihydro-β-erythroidine and the α7-nAChR antagonist methyllycaconitine completely prevented the procognitive actions of TC-2403 and PNU-282987, respectively, varenicline's effect was only partially blocked by any given antagonist. Moreover, the combined treatment with TC-2403 and PNU-282987 more effectively facilitated rats' set-shifting ability than activation of either type of nicotinic acetylcholine receptor alone.

CONCLUSION

The present findings demonstrated that varenicline's actions on both α7-nAChRs and α4β2-nAChRs may be necessary to produce its full procognitive effect in the present experimental setting.

Efficacy and Safety of Varenicline for Smoking Cessation in Schizophrenia: A Meta-Analysis

Objective: Smoking represents a major public health problem among patients with schizophrenia. To this end, some studies have investigated the efficacy of varenicline for facilitating smoking cessation in schizophrenia patients. The present review seeks to synthesize the results of these studies as well as document the reported side effects of using this medication. Methods: An electronic search was performed using five major databases: PubMed, Scopus, EMBASE, Web of Science, and Cochrane Library. Included in the current analysis were randomized clinical trials (RCTs) that have investigated the effect of varenicline in promoting smoking cessation in patients with schizophrenia. Risk of bias among included RCTs was assessed using the Cochrane Collaboration's quality assessment tool. Results: Among the 828 screened articles, only four RCTs, which involved 239 participants, were eligible for meta-analysis. In patients with schizophrenia, varenicline treatment when compared to placebo significantly reduced the number of cigarettes consumed per day [SMD (95% CI) = 0.89(0.57-1.22)] and expired carbon monoxide levels [SMD (95% CI) = 0.50 (0.06-0.94)] respectively. Conclusion: Despite a limited number of studies included in the meta-analysis, our results suggest that varenicline is an effective and safe drug to assist smoking cessation in patients with schizophrenia. Future large-scale well-designed RCTs are required to validate these findings.

Predictors of tobacco abstinence in outpatient smokers with schizophrenia or bipolar disorder treated with varenicline and cognitive behavioral smoking cessation therapy

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.

Effects of varenicline on motor cortical plasticity in non-smokers with schizophrenia

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.

It is feasible and effective to help patients with severe mental disorders to quit smoking: An ecological pragmatic clinical trial with transdermal nicotine patches and varenicline

Despite the proven association between smoking and high rates of medical morbidity and reduced life expectancy in people with severe mental disorders (SMD), their smoking rates do not decline as they do in the general population. We carried out a non-randomized, open-label, prospective, 9-month follow-up multicentre trial to investigate the clinical efficacy, safety and tolerability of a 12-week smoking cessation programme for patients with SMD in the community under real-world clinical conditions. Eighty-two adult outpatients with schizophrenic/bipolar disorder smoking ≥15 cigarettes/day were assigned by shared decision between doctors and patients to transdermal nicotine patches (TNP) [36(46.2%)] or varenicline [39(50%)]. Short-term efficacy: The 12-week 7-day smoking cessation (self-reported cigarettes/day=0 and breath carbon monoxide levels≤9ppm) prevalence was 49.3%, without statistically significant differences between medications (TNP 50.0% vs varenicline 48.6%, chi-square=0.015, p=1.000). Long-term efficacy: At weeks 24 and 36, 41.3 and 37.3% of patients were abstinent, with no statistically significant differences between treatments. Safety and Tolerability: no patients made suicide attempts/required hospitalization. There was no worsening on the psychometric scales. Patients significantly increased weight [TNP 1.1(2.8) vs varenicline 2.5(3.3), p=0.063], without significant changes in vital signs/laboratory results, except significant decreases in alkaline phosphatase and low-density lipoprotein-cholesterol levels in the varenicline group. Patients under varenicline more frequently presented nausea/vomiting (p<0.0005), patients under TNP experienced skin reactions more frequently (p=0.002). Three patients under varenicline had elevated liver enzymes. In conclusion, we have demonstrated that in real-world clinical settings it is feasible and safe to help patients with stabilized severe mental disorders to quit smoking.

Cancer screening, prevention, and treatment in people with mental illness

People with mental illness die decades earlier in the United States compared with the general population. Most of this disparity is related to preventable and treatable chronic conditions, with many studies finding cancer as the second leading cause of death. Individual lifestyle factors, such as smoking or limited adherence to treatment, are often cited as highly significant issues in shaping risk among persons with mental illness. However, many contextual or systems-level factors exacerbate these individual factors and may fundamentally drive health disparities among people with mental illness. The authors conducted an integrative review to summarize the empirical literature on cancer prevention, screening, and treatment for people with mental illness. Although multiple interventions are being developed and tested to address tobacco dependence and obesity in these populations, the evidence for effectiveness is quite limited, and essentially all prevention interventions focus at the individual level. This review identified only one published article describing evidence-based interventions to promote cancer screening and improve cancer treatment in people with mental illness. On the basis of a literature review and the experience and expertise of the authors, each section in this article concludes with suggestions at the individual, interpersonal, organizational, community, and policy levels that may improve cancer prevention, screening, and treatment in people with mental illness.

Varenicline Effects on Smoking, Cognition, and Psychiatric Symptoms in Schizophrenia: A Double-Blind Randomized Trial

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.

Varenicline for smoking cessation in people with schizophrenia: systematic review and meta-analysis

We performed an updated meta-analysis of randomized double-blind placebo-controlled trials (RCTs) on the effects of varenicline adjuvant therapy for smoking cessation in people with schizophrenia, on the basis of a previous meta-analysis (Tsoi in Cochrane Database Syst Rev 2:CD007253, 2013). We searched PubMed, the Cochrane Library databases, and PsycINFO up to August 1, 2014. RCTs comparing varenicline adjuvant therapy with placebo in schizophrenia were included. The risk ratio (RR), number needed to harm (NNH), and standardized mean differences with its 95% confidence interval (CI) were used. Seven studies (total n = 439), including 6 with only schizophrenia (total n = 352), 1 with both schizophrenia (n = 77) and bipolar disorder (n = 10), were included. Varenicline was not superior to placebo in smoking cessation (RR = 0.79, 95% CI 0.58-1.08, p = 0.14, 5 RCTs, n = 322). Varenicline failed to show its superiority to placebo for overall, positive, negative, and depressive symptoms. Moreover, there was no significant difference in the discontinuation rate due to all causes, clinical deterioration, or side effects between varenicline and placebo. Although varenicline caused less abnormal dreams/nightmares than placebo (RR = 0.47, 95% CI 0.22-0.99, p = 0.05, NNH = not significant, 4 RCTs, n = 288), it caused more nausea (RR = 1.79, 95% CI 1.20-2.67, p = 0.004, NNH = 6, p = 0.004, 6 RCTs, n = 417). We detected no significant difference in suicidal ideation and depression between varenicline and placebo. Our results suggest that although varenicline adjuvant therapy is well tolerated, varenicline is not superior to placebo for smoking cessation in people with schizophrenia. Because of the limited sample sizes of the available studies, future studies will require larger samples to ensure that these findings are generalizable.

Phase II crossover trial of varenicline in mild-to-moderate Alzheimer's disease

BACKGROUND

Evidence supports a role of α4β2 receptors in Alzheimer's disease (AD).

METHODS

This Korean, multicenter, double-blind, two-period (6 weeks each), crossover study randomized participants to the order in which they received varenicline (1 mg twice daily) and placebo. Assessments included AD Assessment Scale-Cognitive Subscale (ADAS-Cog) 75, Neuropsychiatric Inventory (NPI), adverse events (AEs) and Columbia-Suicide Severity Rating Scale (C-SSRS).

RESULTS

For varenicline versus placebo (n = 66 randomized), there was no significant difference in the week 6 least square (LS) mean ADAS-Cog 75 total score (primary endpoint; 18.07 vs. 18.49; p = 0.3873) and a slight worsening in the week 6 LS mean NPI (3.82 vs. 2.55; p = 0.0468), primarily driven by decreased appetite/eating. Common treatment-related AEs were nausea (23.3; 3.4%), vomiting (15.0%; 0) and decreased appetite (15.0; 6.8%).

CONCLUSIONS

Varenicline did not improve cognition, behavior or global change in this population. The most frequent varenicline-associated AEs were gastrointestinal; psychiatric AEs were rare and similar between the groups.

Pharmacotherapy of Co-Occurring Schizophrenia and Substance Use Disorders

Substance use disorders, common in patients with schizophrenia, can lead to poor outcomes. Here we review the literature on the use of antipsychotics in patients with co-occurring schizophrenia and substance use disorder as well as evidence for the use of adjunctive pharmacological treatments targeting substance use in these patients. We also discuss a neurobiological formulation suggesting that the cooccurrence of these disorders may be related to a dysfunction in the dopamine mediated brain reward circuitry. Typical antipsychotics do not appear to decrease substance use in this population. Randomized, controlled trials provide some support for use of the atypical antipsychotic clozapine for co-occurring cannabis use disorder, naltrexone and disulfiram for alcohol use disorder, and also nicotine replacement therapy, sustained-release bupropion and varenicline for tobacco use disorder. Nonetheless, data regarding treatment in patients with these co-occurring disorders are still limited, and many studies reported to date have been either underpowered or did not include a control condition. Further research is needed to evaluate optimal pharmacotherapeutic strategies for this population.

Effect of the Nicotinic α4β2-receptor Partial Agonist Varenicline on Non-invasive Brain Stimulation-Induced Neuroplasticity in the Human Motor Cortex

Nicotine alters cognitive functions in animals and humans most likely by modification of brain plasticity. In the human brain, it alters plasticity induced by transcranial direct current stimulation (tDCS) and paired associative stimulation (PAS), probably by interference with calcium-dependent modulation of the glutamatergic system. We aimed to test this hypothesis further by exploring the impact of the α4β2-nicotinic receptor partial agonist varenicline on focal and non-focal plasticity, induced by PAS and tDCS, respectively. We administered low (0.1 mg), medium (0.3 mg), and high (1.0 mg) single doses of varenicline or placebo medication before PAS or tDCS on the left motor cortex of 25 healthy non-smokers. Corticospinal excitability was monitored by single-pulse transcranial magnetic stimulation-induced motor evoked potential amplitudes up to 36 h after plasticity induction. Whereas low-dose varenicline had no impact on stimulation-induced neuroplasticity, medium-dose abolished tDCS-induced facilitatory after-effects, favoring focal excitatory plasticity. High-dose application preserved cathodal tDCS-induced excitability diminution and focal excitatory PAS-induced facilitatory plasticity. These results are comparable to the impact of nicotine receptor activation and might help to further explain the involvement of specific receptor subtypes in the nicotinic impact on neuroplasticity and cognitive functions in healthy subjects and patients with neuropsychiatric diseases.

Acute effects of mecamylamine and varenicline on cognitive performance in non-smokers with and without schizophrenia

RATIONALE

Nicotinic acetylcholine receptors (nAChRs) have been implicated in the pathophysiology of cognitive deficits in the domains of attention and memory in schizophrenia. While nicotinic agonists and antagonists have been proposed as smoking cessation aids, few comparisons have been made of these agents on cognitive performance in individuals with schizophrenia.

OBJECTIVES

This study investigated the acute effects of a nAChR antagonist, mecamylamine, and partial agonist, varenicline, on cognitive function in non-smokers with and without schizophrenia.

METHODS

Single oral doses of mecamylamine 10 mg, varenicline 1 mg, and placebo were administered 1 week apart in random order to adults with schizophrenia (n = 30) and to healthy volunteers (n = 41) in a double-blind, crossover design. The primary outcome of interest was sustained attention as assessed with hit reaction time variability (HRT-SD) on the identical pairs continuous performance test (CPT-IP).

RESULTS

Mecamylamine worsened performance on CPT-IP HRT-SD, a measure of attention, compared to varenicline in both groups. Performance on mecamylamine was worse than performance on both placebo and varenicline on several additional measures of attention, including CPT-IP hit reaction time (HRT) and random errors at various levels of task difficulty. There was a treatment by diagnosis interaction, such that mecamylamine worsened performance on CPT-IP 2-digit HRT, 3-digit random errors, and 4-digit hit rate compared to placebo and varenicline in participants with schizophrenia; effects not observed in controls.

CONCLUSIONS

These findings support a role for nAChRs in attention and suggest that those with schizophrenia may be particularly sensitive to nAChR blockade.

Pharmacotherapy for smoking cessation: pharmacological principles and clinical practice

Strategies for assisting smoking cessation include behavioural counselling to enhance motivation and to support attempts to quit and pharmacological intervention to reduce nicotine reinforcement and withdrawal from nicotine. Three drugs are currently used as first line pharmacotherapy for smoking cessation, nicotine replacement therapy, bupropion and varenicline. Compared with placebo, the drug effect varies from 2.27 (95% CI 2.02, 2.55) for varenicline, 1.69 (95% CI 1.53, 1.85) for bupropion and 1.60 (95% CI 1.53, 1.68) for any form of nicotine replacement therapy. Despite some controversy regarding the safety of bupropion and varenicline, regulatory agencies consider these drugs as having a favourable benefit/risk profile. However, given the high rate of psychiatric comorbidity in dependent smokers, practitioners should closely monitor patients for neuropsychiatric symptoms. Second-line pharmacotherapies include nortriptyline and clonidine. This review also offers an overview of pipeline developments and issues related to smoking cessation in special populations such as persons with psychiatric comorbidity and pregnant and adolescent smokers.

Cognitive function during nicotine withdrawal: Implications for nicotine dependence treatment

Nicotine withdrawal is associated with deficits in neurocognitive function including sustained attention, working memory, and response inhibition. Several convergent lines of evidence suggest that these deficits may represent a core dependence phenotype and a target for treatment development efforts. A better understanding of the mechanisms underlying withdrawal-related cognitive deficits may lead to improve nicotine dependence treatment. We begin with an overview of the neurocognitive effects of withdrawal in rodent and human models, followed by discussion of the neurobehavioral mechanisms that are thought to underlie these effects. We then review individual differences in withdrawal-related neurocognitive effects including genetics, gender, and psychiatric comorbidity. We conclude with a discussion of the implications of this research for developing improved therapies, both pharmacotherapy and behavioral treatments, that target cognitive symptoms of nicotine withdrawal. This article is part of a Special Issue entitled 'NIDA 40th Anniversary Issue'.

Varenicline treatment of concurrent alcohol and nicotine dependence in schizophrenia: a randomized, placebo-controlled pilot trial

Alcohol and nicotine dependence are common in schizophrenia. Varenicline is effective in smoking cessation and has also been shown to decrease alcohol consumption in smokers. The present pilot study assessed the safety and effectiveness of varenicline for treatment of concurrent nicotine and alcohol dependence in schizophrenia. Outpatients with schizophrenia or schizoaffective disorder and concurrent alcohol and nicotine dependence were enrolled in this 8-week, double-blind, randomized, placebo-controlled trial. Alcohol use and smoking were assessed using self-report (Timeline Follow-Back) and biological measures. Adverse events were recorded. Changes in the number of standard drinks per week and cigarettes per week were compared in the 2 groups. Because of safety concerns or loss to follow-up, of 55 patients enrolled, only 10 started study medication, 5 each on varenicline and placebo. Gastrointestinal adverse effects, such as severe abdominal pain, limited study completion to only 4 subjects. Number of standard alcoholic drinks consumed per week decreased by [mean (SD)] 16.6 (20.1) in the varenicline group and by 2.4 (27.4) in the placebo group. Mean (SD) number of cigarettes smoked per week decreased by 66 (65) in the varenicline group and by 47 (77) in the placebo group. Varenicline treatment of concurrent alcohol and nicotine dependence in schizophrenia may be problematic because of safety concerns limiting recruitment and poor tolerability (gastrointestinal adverse effects) limiting retention. There was no increased number of serious neuropsychiatric adverse events in the varenicline group. Based on this small sample, concurrent alcohol and nicotine dependence in schizophrenia may present special obstacles to successful treatment with varenicline.

A Review of Varenicline's Efficacy and Tolerability in Smoking Cessation Studies in Subjects with Schizophrenia

Schizophrenia is a severe psychiatric disorder affecting 1% of the world's population. Nicotine addiction is one of the most important health concerns for patients with schizophrenia. An extensive body of evidence points to a high prevalence rate of comorbid nicotine addiction in people with schizophrenia (70-90%), which contributes to significant cardiovascular and cancer risks in this vulnerable population. Therefore, effective smoking cessation strategies could play a major role in preventing significant morbidity and mortality in this population. Two of the most common pharmacological approaches to smoking cessation, bupropion and nicotine replacement therapy (NRT), have been used in psychiatric patients to reduce their smoking. In 2006, varenicline, a partial agonist of α4β2 acetylcholine receptor, was approved for smoking cessation by the FDA. This drug not only has the beneficial effects on withdrawal symptoms, but also reduces craving and rewarding effects of smoking. While varenicline has been shown to be an effective, safe medication for the general population, its efficacy and safety for subjects with schizophrenia is less well characterized. A number of case studies have prompted FDA warnings about the potential exacerbation of psychiatric symptoms. However, other case studies and pilot studies have shown varenicline to be a safe and effective treatment for smoking cessation in subjects with schizophrenia. Varenicline has the potential to reduce smoking in subjects with schizophrenia, however, clinicians should carefully monitor patients receiving varenicline for potential exacerbation of psychiatric symptoms.