Brain stimulation methods to treat tobacco addiction

BACKGROUND

Tobacco smoking is the leading cause of preventable deaths worldwide, but many smokers are simply unable to quit. Psychosocial and pharmaceutical treatments have shown modest results on smoking cessation rates, but there is an urgent need to develop treatments with greater efficacy. Brain stimulation methods are gaining increasing interest as possible addiction therapeutics.

OBJECTIVES

The purpose of this paper is to review the studies that have evaluated brain stimulation techniques on tobacco addiction, and discuss future directions for research in this novel area of addiction interventions.

METHODS

Electronic and manual literature searches identified fifteen studies that administered repetitive transcranial magnetic stimulation (rTMS), cranial electrostimulation (CES), transcranial direct current stimulation (tDCS) or deep brain stimulation (DBS).

RESULTS

rTMS was found to be the most well studied method with respect to tobacco addiction. Results indicate that rTMS and tDCS targeted to the dorsolateral prefrontal cortex (DLPFC) were the most efficacious in reducing tobacco cravings, an effect that may be mediated through the brain reward system involved in tobacco addiction. While rTMS was shown to reduce consumption of cigarettes, as yet no brain stimulation technique has been shown to significantly increase abstinence rates. It is possible that the therapeutic effects of rTMS and tDCS may be improved by optimization of stimulation parameters and increasing the duration of treatment.

CONCLUSION

Although further studies are needed to confirm the ability of brain stimulation methods to treat tobacco addiction, this review indicates that rTMS and tDCS both represent potentially novel treatment modalities.

Smoking cue reactivity in adult smokers with and without depression: a pilot study

Little is known about the relationship between Major Depressive Disorder (MDD) and smoking-related behaviors such as cue-induced urges to smoke. The purpose of this pilot study was to examine: (1) differences in smoking cue reactivity by MDD history and (2) the association of a diagnosis of MDD, current depressive symptoms, and smoking variables to cue-induced urges to smoke. Participants (N = 52) were n = 31 smokers with no MDD history and n = 21 smokers with past MDD. Participants completed a 2-hour laboratory session during which they were exposed to neutral (eg, pencils) and smoking cues (eg, cigarettes) after smoking one of their preferred brand cigarettes (Satiated Condition) and when it had been 1 hour since they smoked (Brief Deprivation Condition). Cue-induced urges increased with exposure to smoking cues and this increase did not significantly differ by diagnosis group. Current symptoms of depression, but not a diagnosis of MDD, were significantly and positively related to cue-induced cravings in satiated adult smokers. The association between depression symptoms and smoking urges was not significant in the Brief Deprivation Condition. Smoking cue reactivity may be a useful procedure for studying aspects of smoking behavior in adults with depression.

Reproducibility of the nicotine metabolite ratio in cigarette smokers

BACKGROUND

The nicotine metabolite ratio (NMR or 3-hydroxycotinine/cotinine) has been used to phenotype CYP2A6-mediated nicotine metabolism. Our objectives were to analyze (i) the stability of NMR in plasma, saliva, and blood in various storage conditions, (ii) the relationship between NMRs derived from blood, plasma, saliva, and urine, and (iii) the reproducibility of plasma NMR in ad libitum cigarette smokers.

METHODS

We analyzed data from four clinical studies. In studies 1 and 2, we assessed NMR stability in saliva and plasma samples at room temperature (~22°C) over 14 days and in blood at 4°C for up to 72 hours. In studies 2 and 3, we used Bland-Altman analysis to assess agreement between blood, plasma, saliva, and urine NMRs. In study 4, plasma NMR was measured on six occasions over 44 weeks in 43 ad libitum smokers.

RESULTS

Reliability coefficients for stability tests of NMR in plasma and saliva at room temperature were 0.97 and 0.98, respectively, and 0.92 for blood at 4°C. Blood NMR agreed consistently with saliva and plasma NMRs but showed more variability in relation to urine NMR. The reliability coefficient for repeated plasma NMR measurements in smokers was 0.85.

CONCLUSION

The NMR is stable in blood, plasma, and saliva at the conditions tested. Blood, plasma, and saliva NMRs are similar whereas urine NMR is a good proxy for these NMR measures. Plasma NMR was reproducible over time in smokers.

IMPACT

One measurement may reliably estimate a smoker's NMR for use as an estimate of the rate of nicotine metabolism.

A randomized, double-blind, placebo-controlled study evaluating the safety and efficacy of varenicline for smoking cessation in patients with schizophrenia or schizoaffective disorder

OBJECTIVE

Effective smoking cessation treatments are needed for patients with schizophrenia, who, compared with the general population, have high rates of cigarette smoking and more difficulty quitting. We evaluated the safety and efficacy of varenicline for smoking cessation in outpatients with stable schizophrenia or schizoaffective disorder.

METHOD

In this 12-week, randomized, double-blind, multicenter trial (May 8, 2008, to April 1, 2010), 127 smokers (≥ 15 cigarettes/d) with DSM-IV-confirmed schizophrenia or schizoaffective disorder received varenicline or placebo (2:1 ratio). The primary outcome was safety and tolerability of varenicline assessed by adverse events frequency and changes in ratings on the Positive and Negative Syndrome Scale and other psychiatric scales from baseline to 24 weeks. Abstinence was defined as no smoking 7 days prior to weeks 12 and 24, verified by carbon monoxide level.

RESULTS

Eighty-four participants received varenicline; 43, placebo. At 12 weeks (end of treatment), 16/84 varenicline-treated patients (19.0%) met smoking cessation criteria versus 2/43 (4.7%) for placebo (P = .046). At 24 weeks, 10/84 (11.9%) varenicline-treated and 1/43 (2.3%) placebo-treated patients, respectively, met abstinence criteria (P = .090). Total adverse event rates were similar between groups, with no significant changes in symptoms of schizophrenia or in mood and anxiety ratings. Rates of suicidal ideation adverse events were 6.0% (varenicline) and 7.0% (placebo) (P = 1.0). There was 1 suicide attempt by a varenicline patient with a lifetime history of similar attempts and no completed suicides.

CONCLUSIONS

Varenicline was well tolerated, with no evidence of exacerbation of symptoms, and was associated with significantly higher smoking cessation rates versus placebo at 12 weeks. Our findings suggest varenicline is a suitable smoking cessation therapy for patients with schizophrenia or schizoaffective disorder.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT00644969.

A Review of Smoking Cessation in Bipolar Disorder: Implications for Future Research

Tobacco smoking is common in people with bipolar disorder, and rates of smoking cessation are lower than in the general population. A literature review found eleven clinical research publications on bipolar disorder and tobacco, including only one smoking cessation pharmacotherapy trial. This article will review these findings and discuss possible reasons for the high rates of tobacco addiction among persons with bipolar disorder, as well as specific vulnerability factors that may contribute to tobacco treatment failure. An approach to the clinical assessment and treatment of tobacco dependence is described for this sub-group of smokers. Finally, recommendations are made for planning future treatment studies in persons with bipolar disorder and nicotine dependence.

Effects of cigarette smoking status on delay discounting in schizophrenia and healthy controls

BACKGROUND

Delay discounting is a measure of future-oriented decision-making and impulsivity. Cigarette smoking is associated with rapid discounting of the value of delayed outcomes. In schizophrenia, however, cigarette smoking improves certain neurocognitive impairments associated with the disorder which may explain the high smoking rates in this population. This study examined the relationship between cigarette smoking and delay discounting in schizophrenia and control participants.

METHODS

A total of N=130 participants, including those with schizophrenia (n=68) and healthy controls (n=62) were assessed on the Kirby Delay Discounting Task and compared across smoking status (smokers; non-smokers) and smoking history (current, former; never smokers).

RESULTS

Smokers exhibited higher discounting rates (i.e., were more impulsive) than non-smokers of the same diagnostic group. Current and former smokers with schizophrenia exhibited similar and significantly higher discounting rates than never smokers, suggesting that in schizophrenia delay discounting is a trait-dependent phenomenon independent of current cigarette smoking. Consistent with previous studies, there was a trend for higher discounting rates in control current smokers compared to control former and never smokers.

CONCLUSIONS

Smokers with and without schizophrenia have higher rates of delay discounting than non-smokers. However, in schizophrenia, rapid delay discounting appears to be a trait associated with having ever been a smoker (i.e., current and former smoking).

Repetitive transcranial magnetic stimulation and drug addiction

Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive brain stimulation technique that is now being tested for its ability to treat addiction. This review discusses current research approaches and results of studies which measured the therapeutic use of rTMS to treat tobacco, alcohol and illicit drug addiction. The research in this area is limited and therefore all studies evaluating the therapeutic use of rTMS in tobacco, alcohol or illicit drug addiction were retained including case studies through NCBI PubMed ( http://www.ncbi.nlm.nih.gov ) and manual searches. A total of eight studies were identified that examined the ability of rTMS to treat tobacco, alcohol and cocaine addiction. The results of this review indicate that rTMS is effective in reducing the level of cravings for smoking, alcohol, and cocaine when applied at high frequencies to the dorsolateral prefrontal cortex (DLPFC). Furthermore, these studies suggest that repeated sessions of high frequency rTMS over the DLPFC may be most effective in reducing the level of smoking and alcohol consumption. Although work in this area is limited, this review indicates that rTMS is a promising modality for treating drug addiction.

Monoamine oxidase A binding in the prefrontal and anterior cingulate cortices during acute withdrawal from heavy cigarette smoking

CONTEXT

Greater prefrontal cortex and anterior cingulate cortex monoamine oxidase A (MAO-A) binding is associated with depressed mood. Substances in cigarette smoke, such as harman, inhibit MAO-A, and cigarette withdrawal is associated with depressed mood. Dysphoria during cigarette withdrawal predicts relapse. It is unknown whether MAO-A binding increases during early cigarette withdrawal.

OBJECTIVES

To measure prefrontal and anterior cingulate cortex MAO-A binding during acute cigarette withdrawal and to assess the relationship with smoking severity, plasma levels of harman, and severity of depression.

DESIGN

Study via positron emission tomography of healthy control and cigarette-smoking individuals.

PATIENTS

Twenty-four healthy nonsmoking and 24 otherwise healthy cigarette-smoking individuals underwent positron emission tomography with harmine labeled with carbon 11. Healthy nonsmoking individuals underwent scanning once. Cigarette-smoking individuals underwent scanning after acute withdrawal and after active cigarette smoking. Cigarette smoking was heavy (≥25 cigarettes per day) or moderate (15-24 cigarettes per day).

SETTING

Tertiary care psychiatric hospital.

MAIN OUTCOME MEASURE

An index of MAO-A density, MAO-A V(T), was measured in the prefrontal and anterior cingulate cortices.

RESULTS

In heavy-smoking individuals, prefrontal and anterior cingulate cortex MAO-A V(T) was greater during withdrawal (23.7% and 33.3%, respectively; repeated-measures multivariate analysis of variance, F(1,22) = 25.58, P < .001). During withdrawal from heavy smoking, prefrontal and anterior cingulate cortex MAO-A V(T) was greater than in healthy controls (25.0% and 25.6%, respectively; multivariate analysis of variance, F(2,33) = 6.72, P = .004). The difference in MAO-A V(T) in the prefrontal cortex and anterior cingulate cortex between withdrawal and active, heavy smoking covaried with change in plasma harman levels in the prefrontal cortex and anterior cingulate cortex (multivariate analysis of covariance, F(1,10) = 9.97, P = .01). The change in MAO-A V(T) between withdrawal and active, heavy smoking also covaried with severity of depression (multivariate analysis of covariance, F(1,10) = 11.91, P = .006).

CONCLUSIONS

The increase in prefrontal and anterior cingulate cortex MAO-A binding and associated reduction in plasma harman level represent a novel, additional explanation for depressed mood during withdrawal from heavy cigarette smoking. This finding resolves a longstanding paradox regarding the association of cigarette smoking with depression and suicide and argues for additional clinical trials on the effects of MAO-A inhibitors on quitting heavy cigarette smoking.

Neuropsychological performance in patients with schizophrenia and controls as a function of cigarette smoking status

Schizophrenia is associated with many neurocognitive deficits, some of which are improved by nicotine and cigarette smoking. To better understand the relationship between smoking and cognitive function in schizophrenia, cross-sectional assessment of neuropsychological performance as a function of smoking status (smoker or non-smoker) and smoking history (current, former or never-smoker) in clinically stable outpatients with schizophrenia and controls was evaluated. Subjects (n=140) were divided into subgroups on the basis of self-report and biochemical verification of smoking history. Current smokers with schizophrenia (n=38), former smokers with schizophrenia (n=17), never-smokers with schizophrenia (n=12), control smokers (n=31), control former smokers (n=16), and control never-smokers (n=26) were administered a comprehensive neuropsychological battery. Smokers were studied under non-deprivation conditions. Comparison of neuropsychological performance in schizophrenia and control subjects revealed significant main effects of diagnosis. Analysis of the data as a function of smoking history demonstrated that never-smokers with schizophrenia performed the poorest on measures of sustained attention, processing speed and response inhibition, when compared to the other schizophrenia subgroups. Cigarette smoking did not alter neuropsychological performance in controls. Our findings suggest that smoking status and history differentially alters neuropsychological outcomes in schizophrenia compared to non-psychiatric controls, and that never-smokers may present with more severe neurocognitive impairments.

Pharmacogenetics of alcohol, nicotine and drug addiction treatments

The numerous premature deaths, medical complications and socio-economic repercussions of drug and alcohol addiction suggest that improvements in treatment strategies for addictive disorders are warranted. The use of pharmacogenetics to predict response to medication, side effects and appropriate dosages is relatively new in the field of drug addiction. However, increasing our understanding of the genetic factors influencing these processes may improve the treatment of addiction in the future. We examined the available scientific literature on pharmacogenetic advancements in the field of drug addiction with a focus on alcohol and tobacco to provide a summary of genes implicated in the effectiveness of pharmacotherapy for addiction. In addition, we reviewed pharmacogenetic research on cocaine and heroin dependence. Thus far, the most promising results were obtained for polymorphisms in the OPRM1 and CYP2A6 genes, which have been effective in predicting clinical response to naltrexone in alcoholism and nicotine replacement therapy in smoking, respectively. Opinions differ as to whether pharmacogenetic testing should be implemented in the clinic at this time because clinical utility and cost-effectiveness require further investigation. However, the data summarized in this review demonstrate that pharmacogenetic factors play a role in response to addiction pharmacotherapy and have the potential to aid in the personalization of addiction treatments. Such data may lead to improved cessation rates by allowing physicians to select medications for individuals based, at least in part, on genetic factors that predispose to treatment success or failure rather than on a trial and error basis.

The effects of cannabis use on neurocognition in schizophrenia: a meta-analysis

Patients with schizophrenia frequently report cannabis use, yet its effects on neurocognitive functioning in this population are still unclear. This meta-analysis was conducted to determine the magnitude of effect of cannabis consumption on cognition in schizophrenia without the confounding effects of other co-morbid substance use disorders. Eight studies met inclusion criteria yielding a total sample of 942. Three hundred and fifty six of these participants were cannabis users with schizophrenia, and 586 were patients with no cannabis use. Neuropsychological tests were grouped into seven domains (general cognitive ability and intelligence; selective, sustained and divided attention; executive abilities; working memory and learning; retrieval and recognition; receptive and expressive language abilities and visuo-spatial and construction abilities). Effect sizes were computed for each cognitive domain between cannabis-using patients and patients with no history of cannabis use. Effect size differences in cognitive performance in the schizophrenia group as a function of cannabis use were in the small to medium range, denoting superior performance in cannabis-using patients. Explanations for these findings are discussed and suggestions for future research in this area are recommended.

Differences in smoking expectancies in smokers with and without a history of major depression

Adults with depression evidence higher rates of smoking and lower quit rates than adults without depression. Little is known about the relationship between depression and smoking beliefs which are associated with both smoking and smoking cessation behavior. The primary aim of this study was to examine whether adult smokers with and without a history of major depressive disorder (MDD) differ in their endorsement of smoking expectancies. The secondary aim of the study was to examine whether there were interactions of depression and gender on the endorsement of expectancies. Adult cigarette smokers participating in a clinical trial of Selegiline hydrochloride for smoking cessation were classified as having a history of depression (MDD+, n=26) or no history of depression (MDD-, n=75). History of depression and smoking expectancies were assessed prior to randomization into the clinical trial. There was a main effect of depression on 7 out of 10 of the assessed beliefs. MDD+ smokers, compared to MDD- smokers, more strongly endorsed beliefs that smoking reduces negative affect, boredom, and cravings; smoking increases stimulation and social facilitation; smoking helps to manage cravings and weight; and that the taste is enjoyable. The main effect of gender and the interactive effect of depression and gender were not significant. Incorporating expectancies into cognitive-behavioral treatments for smoking cessation may be useful for smokers with a history of depression.

A tobacco reconceptualization in psychiatry: toward the development of tobacco-free psychiatric facilities

Tobacco dependence is the leading cause of death in persons with psychiatric and substance use disorders. This has lead to interest in the development of pharmacological and behavioral treatments for tobacco dependence in this subset of smokers. However, there has been little attention paid to the development of tobacco-free environments in psychiatric institutions despite the creation of smoke-free psychiatric hospitals mandated by the Joint Commission for Accreditation of Health Organizations (JCAHO) in 1992. This review article addresses the reasons why tobacco should be excluded from psychiatric and addictions treatment settings, and strategies that can be employed to initiate and maintain tobacco-free psychiatric settings. Finally, questions for further research in this field are delineated. This Tobacco Reconceptualization in Psychiatry is long overdue, given the clear and compelling benefits of tobacco-free environments in psychiatric institutions.

Impact of a smoke-free policy in a large psychiatric hospital on staff attitudes and patient behavior

OBJECTIVE

The objectives of this work were to examine changes over time in degree of staff support for the implementation of a smoke-free policy in Canada's largest public mental health and addiction teaching hospital and to assess the impact of the policy on patient behavior.

METHOD

Staff completed an anonymous survey, which assessed views toward the smoke-free policy and perceived change in patient behavior, 2-7 and 31-33 months after an indoor smoke-free policy was implemented (September 21, 2005). Objective indicators of patient behavior were also collected in the form of number of emergency code whites (aggressive behavior) and that of code reds (fire) called 1 year prior to and 2 years following policy implementation.

RESULTS

Survey response rates were 19.0% (n=481) and 18.1% (n=500) at 2-7 and 31-33 months, respectively. The proportion of staff who supported the policy increased from pre-implementation (82.6%) to post-implementation (89.1%), and a high level of support was maintained 2 years after policy enactment (90.1%). The number of emergency codes did not significantly change after policy implementation, and staff did not perceive a change in most forms of patient behavior.

CONCLUSION

A smoke-free policy can be implemented in a large psychiatric hospital with a high degree of support from staff and no substantial negative impact on patient behavior.

Individualized smoking cessation treatment in an outpatient setting: Predictors of outcome in a sample with psychiatric and addictions co-morbidity

OBJECTIVE

Patients with psychiatric disorders have higher rates of smoking and greater difficulty quitting smoking. However, few studies have compared patients with schizophrenia or schizoaffective disorders to patients with other psychiatric diagnoses without psychosis, addressing ability to quit and differences in treatment characteristics.

METHOD

A retrospective chart review was conducted on a sample of 165 cigarette smokers admitted to an outpatient smoking cessation clinic located in a large inner-city psychiatric hospital. Patients with schizophrenia and schizoaffective disorder (n=55) were matched for age and sex at a ratio of 1:2 with a comparison group without psychosis (n=110) from the same clinic. Primary outcomes of interest were quit status (7-day point prevalence) and significant reduction in cigarettes per day (>or=50% but not quit) at final treatment session.

RESULTS

There were no significant differences between groups for end-of-treatment quit rate or significant reduction (>or=50%) in cigarettes per day. Patients with schizophrenia made significantly more visits to the clinic and were in treatment for a longer period of time. A greater number of individual treatment sessions and being male were the most significant predictors of cessation.

CONCLUSION

Patients with schizophrenia were as likely to quit smoking as a comparison group of patients with a high rate of other psychiatric comorbidities without psychosis. Findings suggest treatment success in this population requires an extended number of clinic visits, group therapy, and possibly higher doses of nicotine replacement.

Changes in smoking expectancies in abstinent, reducing, and non-abstinent participants during a pharmacological trial for smoking cessation

INTRODUCTION

Smoking expectancies are related to smoking consumption and predict smoking cessation. Little is known about whether expectancies change during smoking treatments, consistent with changes in smoking behavior. This study examined reported changes in smoking beliefs during an 8-week smoking cessation trial, which evaluated the safety and efficacy of the monoamine oxidase B inhibitor selegiline hydrochloride versus placebo.

METHODS

Participants were classified as "Quit" (n = 18), "Reduced" (n = 34), or "Not Quit" (n = 49) by 7-day point prevalence abstinence at the end of treatment. Expectancies were assessed at randomization, 1 week after the target quit date, and at the end of treatment.

RESULTS

Beliefs about smoking assessed prior to the quit attempt were not associated with cessation outcomes. Participants who quit smoking reported a reduction in expectations that smoking would reduce negative affect, boredom, and cravings, and facilitate social interactions, while participants who did not quit smoking reported an increase in Negative Social Impression beliefs. There were gender differences in beliefs related to Negative Affect Reduction, Negative Physical Feelings, Social Facilitation, and Cravings and significant Gender X Smoking Status interactions for Health Risk and Weight Control beliefs. There were no significant effects of medication on expectancies.

DISCUSSION

Baseline expectancies were not associated with abstinence outcomes; however, expectancies changed over time with changes in smoking, and the greatest changes were seen with smoking abstinence. Information about the relationship between smoking beliefs and behaviors may be used to enhance or tailor smoking cessation treatments.

A double-blind, placebo-controlled, randomized clinical trial of oral selegiline hydrochloride for smoking cessation in nicotine-dependent cigarette smokers

AIM

The primary aim of this study was to determine the safety and efficacy of the monoamine oxidase-B (MAO-B) inhibitor selegiline hydrochloride (SEL, l-Deprenyl; Eldepryl) as an aid for smoking cessation in cigarette smokers.

METHODS

One hundred and one nicotine-dependent adult cigarette smokers without current psychiatric or substance use disorders participated in this 8-week randomized, double-blind, placebo-controlled trial. Participants received either SEL (5mg bid, n=51) or placebo (PLO, n=50), in combination with brief (<10 min) manualized smoking cessation counseling. The main smoking outcome measures were 7-day point prevalence abstinence at end of trial (EOT), 4-week continuous smoking abstinence at end of trial (CA), and 7-day point prevalence abstinence at 6-month follow-up (6MFU). Abstinence was determined by an absence of self-reported cigarette smoking and biochemically verified by expired breath carbon monoxide and plasma cotinine levels.

RESULTS

Rates of smoking abstinence did not differ by medication group (EOT: SEL=16%, PLO=20%, p=0.57; CA: SEL=14%, PLO=18%, p=0.56; 6MFU: SEL=12%, PLO=16%, p=0.54). Adverse events were modest and comparable between medication groups. Participants receiving SEL were more likely than those receiving PLO to report dry mouth (25.5% versus 8.2%, p<0.05).

CONCLUSIONS

Our results suggest that SEL was safe and well-tolerated by adult cigarette smokers, but did not improve smoking abstinence rates compared to PLO.

Mecamylamine - a nicotinic acetylcholine receptor antagonist with potential for the treatment of neuropsychiatric disorders

Mecamylamine (Inversine), the first orally available antihypertensive agent launched in the 1950s, is rarely used today for hypertension because of its widespread ganglionic side effects at antihypertensive doses (25 - 90 mg/day). However, more recent clinical studies suggest that mecamylamine is effective at much lower doses for blocking the central and peripheral effects of nicotine. Pharmacologically, mecamylamine has been well characterized as a nonselective and noncompetitive antagonist of nicotinic acetylcholine receptors (nAChRs). Because mecamylamine easily crosses the blood - brain barrier at relatively low doses (2.5 - 10 mg), it has been used by several research groups over the past two decades investigating the role of central nAChRs in the etiology and treatment of various neuropsychiatric disorders, including addiction disorders, Tourette's syndrome, schizophrenia and various cognitive and mood disorders. Two independent Phase II clinical trials recently confirmed mecamylamine's hypothesized antidepressant activity and suggest that it may be effective as an augmentation pharmacotherapy for SSRI treatment resistant major depression. These areas of investigation for mecamylamine are reviewed and recommendations for future research directions are proposed.

Effects of the nicotinic receptor antagonist mecamylamine on ad-lib smoking behavior, topography, and nicotine levels in smokers with and without schizophrenia: a preliminary study

Individuals with schizophrenia have higher plasma nicotine levels in comparison to non-psychiatric smokers, even when differences in smoking are equated. This difference may be related to how intensely cigarettes are smoked but this has not been well studied. Mecamylamine (MEC), a non-competitive nicotinic acetylcholine receptor (nAChR) antagonist, which has been shown to increase ad-lib smoking and to affect smoking topography, was used in the current study as a pharmacological probe to increase our understanding of smoking behavior, smoking topography, and resulting nicotine levels in smokers with schizophrenia. This preliminary study used a within-subject, placebo-controlled design in smokers with schizophrenia (n=6) and healthy control smokers (n=8) to examine the effects of MEC (10mg/day) on ad-lib smoking behavior, topography, nicotine levels, and tobacco craving across two smoking deprivation conditions (no deprivation and 12-h deprivation). MEC, compared to placebo, increased the number of cigarettes smoked and plasma nicotine levels. MEC increased smoking intensity and resulted in greater plasma nicotine levels in smokers with schizophrenia compared to controls, although these results were not consistent across deprivation conditions. MEC also increased tobacco craving in smokers with schizophrenia but not in control smokers. Our results suggest that antagonism of high-affinity nAChRs in smokers with schizophrenia may prompt compensatory smoking, increasing the intensity of smoking and nicotine exposure without alleviating craving. Further work is needed to assess whether nicotine levels are directly mediated by how intensely the cigarettes are smoked, and to confirm whether this effect is more pronounced in smokers with schizophrenia.

Correlation of prepulse inhibition and Wisconsin Card Sorting Test in schizophrenia and controls: effects of smoking status

BACKGROUND

In schizophrenia, neurocognitive deficits associated with the illness are modulated by tobacco smoking. However, little is known about how smoking status modulates the relationships between neurocognitive measures in schizophrenia and healthy control subjects.

OBJECTIVE

The goal of this study was to evaluate the relationship between sensorimotor gating assessed by prepulse inhibition (PPI) and executive cognitive function using the Wisconsin Card Sorting Test (WCST) in schizophrenia and controls as a function of smoking status.

METHOD

We studied PPI and neuropsychological function in four groups (N=50); smokers with schizophrenia (SS; n=15), control smokers (CS; n=13), non-smokers with schizophrenia (SNS; n=11) and control non-smokers (CNS; n=11).

RESULTS

SNS demonstrated the poorest PPI, while SS showed comparably high levels of PPI to CNS. Non-psychiatric controls outperformed patients on WCST outcomes irrespective of smoking status. Several prefrontal outcome measures on the WCST (categories completed, percentage perseverative and non-perseverative errors) correlated significantly with PPI at the 60 and 120 ms prepulse intervals. In contrast, there were no significant correlations between PPI and any WCST outcomes in SNS, CS or CNS, and few significant correlations between PPI and other neuropsychological measures.

DISCUSSION

Our preliminary data suggests that the correlation between sensorimotor gating (PPI) and prefrontal executive cognitive functioning (WCST) is enhanced by acute cigarette smoking in schizophrenia.

Prefrontal cognitive dysfunction is associated with tobacco dependence treatment failure in smokers with schizophrenia

BACKGROUND

Patients with schizophrenia have higher rates of smoking (58-88%) than in the general population ( approximately 22%), and are more refractory to smoking cessation. These patients also exhibit numerous neurocognitive deficits, some of which may be ameliorated by cigarette smoking. The neurocognitive benefits derived from nicotine may, in turn, contribute to elevated rates of smoking and smoking persistence in schizophrenia. The present study examined the relationship between neurocognitive function and smoking cessation in schizophrenia.

METHODS

Treatment-seeking smokers with schizophrenia (N=58) participated in a 10-week placebo-controlled trial of sustained-release (SR) bupropion plus transdermal nicotine patch. Neuropsychological performance was evaluated in a subset of patients (n=31), prior to pharmacological treatment, using a neurocognitive battery.

RESULTS

Subjects were compared as a function of endpoint smoking status (Quit versus Not Quit), assessed by end of trial 7-day point prevalence abstinence, confirmed by CO level (< 10 ppm) on demographic traits, smoking, and clinical outcomes. While there were no significant baseline differences between quitters and non-quitters, non-quitters exhibited significantly greater deficits in performance on Trail Making Test, Part B (p=0.01) and on Digit Span backwards (p=0.04) compared to quitters. No associations were found between quit status and performance on other neuropsychological measures.

CONCLUSIONS

Our findings extend results of previous studies which suggest deficits in frontal executive function are associated with smoking cessation failure in schizophrenia. This may have implications for the development of tailored smoking cessation treatments in this population.