The influence of stress on psychopharmacological responses to nicotine

Chronic Smoking, Trait Anxiety, and the Physiological Response to Stress

BACKGROUND AND OBJECTIVES

Both chronic smoking and trait anxiety have been associated with dysregulations in psychobiological stress response systems. However, these factors have not been studied in conjunction. We expected trait anxiety and smoking status to attenuate stress reactivity. Furthermore, we expected an allostatic load effect resulting in particularly attenuated stress reactivity in high-anxious smokers. In addition, high-anxious smokers were expected to exhibit increased urges to smoke in response to stress.

METHODS

115 smokers and 37 nonsmokers, aged 18-64 years, completed a laboratory session including mental stressors such as evaluated public speaking and mental arithmetic. Trait anxiety was assessed using Spielberger's State-Trait Anxiety Inventory. Cardiovascular autonomic indices, salivary cortisol, and the desire to smoke were measured at baseline, during stressors, and at recovery.

RESULTS

Regression analyses showed that smokers exhibited attenuated cardiovascular stress responses in comparison to nonsmokers. Higher trait anxiety predicted attenuated systolic blood pressure responses to stress. No interaction effect of smoking status and trait anxiety was found in stress response measures. Higher trait anxiety predicted an increased desire to smoke in response to stress among smokers.

CONCLUSION

Results indicate that both smoking status and trait anxiety are associated with blunted sympatho-adrenal cardiovascular stress reactivity. Elevated urges to smoke in response to stress found among smokers with high trait anxiety suggest an important role of anxiety in smoking propensity and relapse.

Sex differences in conditioned nicotine reward are age-specific

Women constitute half of all smokers and many studies suggest that adult males and females differ in factors that maintain tobacco smoking, yet there is limited information about sex differences in nicotine reward during adolescence. Limited studies suggest that adolescent male rats self-administer more nicotine than adults, suggesting that drug administration during adolescence leads to different behavioral effects than during adulthood. In the present study, male rats developed a significant conditioned place preference (CPP) to lower doses of nicotine than females, regardless of age. In addition, adolescents were more sensitive than adults. In female rats, adolescents exhibited a CPP of greater magnitude than adult females. In males, the magnitude of the CPP did not differ as a function of age, but adolescents exhibited CPP to lower doses than adults. There also were differences in nicotinic acetylcholinergic receptor binding in nucleus accumbens and caudate putamen in response to nicotine across age and sex. These findings suggest that it is necessary to consider sex- and age-specific effects of drugs such as nicotine when developing strategies for improving smoking cessation treatments.

Nicotine affects cutaneous wound healing in stressed mice

Stress is an important condition of modern life. Nicotine addiction can modulate the physiological response to stress. Cutaneous healing is a complex process resulting in scar formation, which can be delayed by stress. Therefore, the aim of this study was to investigate the effects of nicotine administration on cutaneous wound healing in chronically stressed mice. Male mice were submitted to rotational stress, whereas control animals were not subjected to stress. These stressed and control animals were treated with a transdermal nicotine patch that was changed every day. A full-thickness excisional lesion was also generated, and 14 days later, lesions had recovered. However, the Stress + Nicotine group presented a delay in wound contraction. These wounds showed a decrease in inflammatory cell infiltration and lower expression of transforming growth factor-β (TGF-β), whereas there was an increase in angiogenesis and tumor necrosis factor-α (TNF-α) expression. In vitro fibroblast migration was also impaired by the nicotine treatment of stressed-stimulated cells. In conclusion, nicotine administration potentiates the delay in wound closure observed in mice submitted to stress.

Oral Nicotine Self-Administration in Rodents

Nicotine addiction is a complex process that begins with self-administration. Consequently, this process has been studied extensively using animal models. A person is usually not called "smoker" if s/he has smoked for a week or a month in a lifetime; in general, a smoker has been smoking for many years. Furthermore, a smoker has free access to cigarettes and can smoke whenever she/he wants, provided there are no social/legal restraints. Subsequently, in an animal model of tobacco addiction, it will be desirable to expose the animal to free access nicotine for 24 hours/day for many weeks, starting at different stages of development.

A psychobiological framework of the substrates that mediate nicotine use during adolescence

Adolescents are especially likely to initiate tobacco use and are more vulnerable to long-term nicotine dependence. A unifying hypothesis is proposed based largely on animals studies that adolescents, as compared to adults, experience enhanced short-term positive and reduced aversive effects of nicotine, as well as less negative effects during nicotine withdrawal. Thus, during adolescence the strong positive effects of nicotine are inadequately balanced by negative effects that contribute to nicotine dependence in adults. This review provides a neural framework to explain developmental differences within the mesolimbic pathway based on the established role of dopamine in addiction. This pathway originates in the ventral tegmental area (VTA) and terminates in the nucleus accumbens (NAcc) where dopamine is increased by nicotine but decreased during withdrawal. During adolescence, excitatory glutamatergic systems that facilitate dopamine are overdeveloped, whereas inhibitory GABAergic systems are underdeveloped. Thus, it is hypothesized that adolescents display enhanced nicotine reward and reduced withdrawal via enhanced excitation and reduced inhibition of VTA cell bodies that release dopamine in the NAcc. Although this framework focuses on adolescents and adults, it may also apply to the understanding of enhanced vulnerability to nicotine in adults that were previously exposed to nicotine during adolescence. The hypothesis presented in this review suggests that the clinical diagnostic criteria developed for nicotine dependence in adults, based primarily on withdrawal, may be inappropriate during adolescence when nicotine withdrawal does not appear to play a major role in nicotine use. Furthermore, treatment strategies involving nicotine replacement may be harmful for adolescents because it may cause enhanced vulnerability to nicotine dependence later in adulthood.

Guidelines on nicotine dose selection for in vivo research

RATIONALE

This review provides insight for the judicious selection of nicotine dose ranges and routes of administration for in vivo studies. The literature is replete with reports in which a dosaging regimen chosen for a specific nicotine-mediated response was suboptimal for the species used. In many cases, such discrepancies could be attributed to the complex variables comprising species-specific in vivo responses to acute or chronic nicotine exposure.

OBJECTIVES

This review capitalizes on the authors' collective decades of in vivo nicotine experimentation to clarify the issues and to identify the variables to be considered in choosing a dosaging regimen. Nicotine dose ranges tolerated by humans and their animal models provide guidelines for experiments intended to extrapolate to human tobacco exposure through cigarette smoking or nicotine replacement therapies. Just as important are the nicotine dosaging regimens used to provide a mechanistic framework for acquisition of drug-taking behavior, dependence, tolerance, or withdrawal in animal models.

RESULTS

Seven species are addressed: humans, nonhuman primates, rats, mice, Drosophila, Caenorhabditis elegans, and zebrafish. After an overview on nicotine metabolism, each section focuses on an individual species, addressing issues related to genetic background, age, acute vs chronic exposure, route of administration, and behavioral responses.

CONCLUSIONS

The selected examples of successful dosaging ranges are provided, while emphasizing the necessity of empirically determined dose-response relationships based on the precise parameters and conditions inherent to a specific hypothesis. This review provides a new, experimentally based compilation of species-specific dose selection for studies on the in vivo effects of nicotine.

Nicotine antagonizes caffeine- but not pentylenetetrazole-induced anxiogenic effect in mice

RATIONALE

Nicotine and caffeine are widely consumed licit psychoactive drugs worldwide. Epidemiological studies showed that they were generally used concurrently. Although some studies in experimental animals indicate clear pharmacological interactions between them, no studies have shown a specific interaction on anxiety responses.

OBJECTIVES

The present study investigates the effects of nicotine on anxiety induced by caffeine and another anxiogenic drug, pentylenetetrazole, in mice. The elevated plus-maze (EPM) test was used to evaluate the effects of drugs on anxiety.

METHODS

Adult male Swiss Webster mice (25-32 g) were given nicotine (0.05-0.25 mg/kg s.c.) or saline 10 min before caffeine (70 mg/kg i.p.) or pentylenetetrazole (15 and 30 mg/kg i.p.) injections. After 15 min, mice were evaluated for their open- and closed-arm time and entries on the EPM for a 10-min session. Locomotor activity was recorded for individual groups by using the same treatment protocol with the EPM test.

RESULTS

Nicotine (0.05-0.25 mg/kg) itself did not produce any significant effect in the EPM test, whereas caffeine (70 mg/kg) and pentylenetetrazole (30 mg/kg) produced an anxiogenic effect, apparent with decreases in open-arm time and entry. Nicotine (0.25 mg/kg) pretreatment blocked the caffeine- but not pentylenetetrazole-induced anxiety. Administration of each drug and their combinations did not produce any effect on locomotor activity.

CONCLUSIONS

Our results suggest that the antagonistic effect of nicotine on caffeine-induced anxiety is specific to caffeine, instead of a non-specific anxiolytic effect. Thus, it may extend the current findings on the interaction between nicotine and caffeine.

Psychostimulant withdrawal as an inducing condition in animal models of depression

A large body of evidence indicates that the withdrawal from high doses of psychostimulant drugs in humans induces a transient syndrome, with symptoms that appear isomorphic to those of major depressive disorder. Pharmacological treatment strategies for psychostimulant withdrawal in humans have focused mainly on compounds with antidepressant properties. Animal models of psychostimulant withdrawal have been shown to demonstrate a wide range of deficits, including changes in homeostatic, affective and cognitive behaviors, as well as numerous physiological changes. Many of these behavioral and physiological sequelae parallel specific symptoms of major depressive disorder, and have been reversed by treatment with antidepressant drugs. These combined findings provide strong support for the use of psychostimulant withdrawal as an inducing condition in animal models of depression. In the current review we propound that the psychostimulant withdrawal model displays high levels of predictive and construct validity. Recent progress and limitations in the development of this model, as well as future directions for research, are evaluated and discussed.

The effect of nicotine patch therapy on depression in nonsmokers: a preliminary study

Prior uncontrolled studies of nonsmokers with major depressive disorder (MDD) indicate rapid reduction in depressive symptoms with nicotine patch therapy. This randomized, double-blind, placebo-controlled pilot study examined the effect of nicotine patch therapy on depressive symptoms in non-medicated nonsmokers with current MDD. Due to recruitment difficulties, only 7 were enrolled and of these 6 (5 females, 1 male) completed the study. Participants received either placebo (n = 4) or active (n = 2) patch therapy for 8 days. They completed daily clinic visits during patch therapy and a final visit on Day 12. Depressive symptoms were assessed using the Hamilton Rating Scale for Depression (HRSD). The mean change in HRSD scores of all participants decreased (p = 0.021) from baseline by Day 1 of patch use. Similar decreases in HRSD scores were observed for placebo and active patch groups. Among the placebo participants, the mean HRSD score decreased (p = 0.038) by Day 2. The study needs replication with a larger sample and utilizing novel recruitment strategies.

Smoking, stress, and negative affect: correlation, causation, and context across stages of smoking

This transdisciplinary review of the literature addresses the questions, Do stress and negative affect (NA) promote smoking? and Does smoking genuinely relieve stress and NA? Drawing on both human and animal literatures, the authors examine these questions across three developmental stages of smoking--initiation, maintenance, and relapse. Methodological and conceptual distinctions relating to within- and between-subjects levels of analyses are emphasized throughout the review. Potential mechanisms underlying links between stress and NA and smoking are also reviewed. Relative to direct-effect explanations, the authors argue that contextual mediator-moderator approaches hold greater potential for elucidating complex associations between NA and stress and smoking. The authors conclude with recommendations for research initiatives that draw on more sophisticated theories and methodologies.

Cellular and synaptic mechanisms of nicotine addiction

The tragic health effects of nicotine addiction highlight the importance of investigating the cellular mechanisms of this complex behavioral phenomenon. The chain of cause and effect of nicotine addiction starts with the interaction of this tobacco alkaloid with nicotinic acetylcholine receptors (nAChRs). This interaction leads to activation of reward centers in the CNS, including the mesoaccumbens DA system, which ultimately leads to behavioral reinforcement and addiction. Recent findings from a number of laboratories have provided new insights into the biologic processes that contribute to nicotine self-administration. Examination of the nAChR subtypes expressed within the reward centers has identified potential roles for these receptors in normal physiology, as well as the effects of nicotine exposure. The high nicotine sensitivity of some nAChR subtypes leads to rapid activation followed in many cases by rapid desensitization. Assessing the relative importance of these molecular phenomena in the behavioral effects of nicotine presents an exciting challenge for future research efforts.

Absence of alpha7-containing neuronal nicotinic acetylcholine receptors does not prevent nicotine-induced seizures

Nicotine is the primary addictive component in tobacco, and at relatively low doses it affects cardiovascular responses, locomotor activity, thermoregulation, learning, memory, and attention. At higher doses nicotine produces seizures. The mechanisms underlying the convulsive effects of nicotine are not known, but studies conducted on a number of inbred strains of mice have indicated a positive correlation between the number of alpha-bungarotoxin (alpha-BTX) binding sites in the hippocampus and the sensitivity to nicotine-induced seizures. Because alpha7-containing neuronal nicotinic acetylcholine receptors (nAChRs) represent the major binding site for alpha-BTX, mice lacking the alpha7 nAChR subunit were predicted to be less sensitive to the convulsive effects of nicotine. To test this hypothesis, we injected nicotine intraperitoneally in alpha7 mutant mice and found that the dose-response curve for nicotine-induced seizures was similar in the alpha7 +/+, alpha7 +/- and alpha7 -/- mice. The retained sensitivity to the convulsant effects of nicotine could not be explained by the presence of cholinergic compensatory mechanisms such as increases in mRNA levels for other nAChR subunits, or changes in binding levels or affinity for nicotinic ligands such as epibatidine and nicotine. These findings indicate that alpha7 may not be necessary for the mechanisms underlying nicotine-induced seizures.

The effects of nicotine on neural pathways implicated in depression: a factor in nicotine addiction?

The prevalence of tobacco smoking varies considerably between different groups within the community, tobacco smoking being particularly prevalent in patients with depressive disorder. This review will focus on results, derived from animal studies, which suggest that, in addition to its primary reinforcing properties, nicotine also exerts effects in stressful environments, which may account for its enhanced addictive potential in depressed patients. It focuses on the evidence that depression sensitises patients to the adverse effects of stressful stimuli, and that this can be relieved by drugs that stimulate dopamine release in the forebrain. This mechanism, it is proposed, contributes to the increased craving to smoke in abstinent smokers exposed to such stimuli, because they become conditioned to use this property of nicotine to produce rapid alleviation of the adverse effects of the stress. The review also explores the possibility that chronic exposure to nicotine elicits changes in 5-HT formation and release in the hippocampus which are depressogenic. It is postulated that smokers are protected from the consequences of these changes, while they continue to smoke, by the antidepressant properties of nicotine. However, they contribute to the symptoms of depression experienced by many smokers when they first quit the habit.

Cross-sectional study on the relationship between smoking or smoking cessation and trait anxiety

OBJECTIVE

The relationships between trait anxiety, or anxiety proneness, and smoking and between trait anxiety and smoking cessation, among an adult population were investigated.

METHODS

The subjects were 2,669 male Japanese personnel working for a Japanese government agency. Participants completed a self-administered questionnaire on smoking and smoking cessation status and other habits. Trait anxiety was evaluated with the trait anxiety part of the standardized Japanese version of the Spielberger State-Trait Anxiety Inventory. Trait anxiety is regarded as the long-term, more endogenous general type of anxiety. Odds ratios of the single 2 x 2 table were calculated and a logistic regression analysis was used to adjust for age.

RESULTS

After adjusting for age, high trait anxiety did not increase the risk of smoking and was not related to success in abstaining from smoking. More subjects with high trait anxiety had planned to stop smoking (adjusted odds ratio: 1.39, P = 0.01) but did not actually succeed in doing so.

CONCLUSION

The present study did not support the hypothesis that high trait anxiety increased the risk of having a smoking habit and that high trait anxiety increased the chance of abstaining from smoking. However, the study did show that high trait anxiety was related to the planning of smoking cessation, but not to actually giving up the smoking habit.

Reduced dopamine output in the nucleus accumbens but not in the medial prefrontal cortex in rats displaying a mecamylamine-precipitated nicotine withdrawal syndrome

Mesolimbocortical dopamine (DA) neurotransmission is important in the mediation of the dependence-producing actions of nicotine and other drugs of abuse. Withdrawal from chronic treatment with various types of addictive drugs, including amphetamine, cocaine, ethanol and morphine is associated with a decrease in dopaminergic output in the nucleus accumbens (NAC), whereas the effects of withdrawal from these drugs on dopaminergic output in the medial prefrontal cortex (PFC), as yet, remain largely unknown. This study examined putative changes in the extracellular levels of dopamine and its metabolites dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) in the NAC and in the PFC of rats displaying behavioral signs of nicotine withdrawal. Rats were infused for 7 days with nicotine via subcutaneously implanted minipumps, whereas control animals carried saline-containing pumps. On the fifth day of infusion a microdialysis probe was implanted in the NAC or the PFC of the rats. Forty-eight hours later the levels of DA and the monoamine metabolites were assessed in the dialysate. The behavioral and biochemical effects of a saline injection and a subsequent challenge with the nicotinic receptor antagonist mecamylamine (1 mg/kg s.c.) were determined. Following mecamylamine challenge in nicotine-treated animals, the levels of DA, DOPAC and HVA in the NAC, but not in the PFC, decreased below pre-injection levels and in relation to control animals. The score of abstinence signs increased in the nicotine-treated rats, as compared both to the score after saline and to that in control animals. The decreased DA output in the NAC in animals displaying nicotine withdrawal signs is similar to that seen after withdrawal of several other drugs of abuse, and may have bearing on motivational deficits associated with the abstinence reactions.

Attention deficit disorder in adults and nicotine dependence: psychobiological factors in resistance to recovery?

The addictive nature of nicotine appears to depend on a number of psychobiological factors. This study explores the psychoactive effects of nicotine in relationship to the particular dysphoric aspects of Attention Deficit Disorder as a coincident factor in nicotine dependence and resistance to treatment. The psychological and behavioral effects of nicotine directly correspond to reduction in symptoms of Attention-Deficit/Hyperactivity Disorder (ADHD) and the neurochemical effects of nicotine are qualitatively similar to stimulant medications used to treat ADHD. Aspects of the treatment of nicotine or other addictions in such comorbid situations are discussed in the context of self-medication.

The pharmacology of (-)-nicotine and novel cholinergic channel modulators

Advances in the understanding of the molecular biology and pharmacology of nAChRs may provide targets for the development of novel and selective modulators of nAChRs in the brain. This contention is supported by the dissimilar behavioral effects observed following systemic administration of currently available nicotinic ligands. The concept of multiple subtypes of nAChRs is not unique, as evidenced by the pharmacology of other ligand-gated ion channels, such as GABA-A receptor, which also exist in multiple subtypes. At present, with respect to the nAChRs, relatively few of the subtypes identified have been cloned from human tissue and pharmacologically evaluated, but several groups are focusing their research efforts in this direction. With a thorough understanding of the pharmacological and functional characteristics of more of the putative human nAChR subtypes, this knowledge will facilitate the discovery of more efficacious and less toxic ChCMs that may provide potential novel therapeutic agents for a variety of CNS conditions.

N-Methyl-beta-carboline-3-carboxamide (FG 7142): An anxiogenic agent in cigarette smoke condensate and its mechanism of formation

beta-Carboline-3-carboxylic acid methylamide (FG 7142), an anxiogenic agent has been found in cigarette smoke condensate, but not in the cigarette itself. When a cigarette, except its filter portion, was immersed in 20 ml of potassium phosphate buffer, pH 7.4, then heated at 60 degrees C for 2 days with or without presence of methylamine, FG 7142 was detected only in the mixture containing methylamine. Furthermore, when the mixtures of beta-carboline derivatives and various amounts of methylamine hydrochloride were heated at 60 degrees C for 5 days, FG 7142 was formed only in the mixtures containing methylamine and 1-methyl-1,2,3,4-tetrahydro-beta-carboline-3-caroxylic acid (MTCA) or 1,2,3,4-tetrahydro-beta-carboline-3-carboxylic acid (TCCA). FG 7142 was also produced in the mixture of glucose, l-tryptophan and methylamine when heated at 200 degrees C in a dry condition. These observations suggest that FG 7142 is formed through the smoking process and that methylamine in cigarette smoke may play an important role in the formation of FG 7142.

Nicotine modulates effects of stress on acoustic startle reflexes in rats: dependence on dose, stressor and initial reactivity

Cigarette smokers report that one reason for smoking is that smoking helps them cope with stress, but there is conflicting evidence as to whether nicotine reduces physiological and behavioral responses to stress. The acoustic startle reflex amplitude, pre-pulse inhibition, and habituation of the reflex provide quantifiable measures of behavioral reactivity that may be sensitive to stress-induced changes that are altered by nicotine. In the present experiment, rats classified as high and low reactors according to baseline startle amplitudes were administered nicotine (6 or 12 mg/kg/day) or saline by osmotic minipump for 11 days. On day 11, animals were acutely stressed by restraint or observation of restraint of conspecifics prior to startle measurement. Nicotine and stress each independently increased acoustic startle amplitude and amount of pre-pulse inhibition, but in combination, the effect of restraint stress and 12 mg/kg nicotine were indistinguishable from saline-treated, non-stressed controls. In contrast, the 6 mg/kg nicotine dose enhanced effects of both restraint and observation stressors on startle amplitude and pre-pulse inhibition. Animals classified as highly reactive prior to treatment were more responsive to nicotine, stress, and the combination, suggesting that initial reactivity is an important determinant of drug and stress effects. Results indicate that nicotine can both reduce and enhance stress effects on reflex amplitude and pre-pulse inhibition depending upon nicotine dose, stressor, and individual differences in reactivity.

Neural mechanisms underlying nicotine dependence

There is little doubt that many habitual smokers find it difficult to quit the habit because they have become addicted to the nicotine present in the smoke. This paper addresses some of the pharmacological mechanisms underlying this addiction and discusses how an understanding of these mechanisms may contribute to the more effective use of nicotine replacement therapy during smoking cessation. It considers critically the evidence that the "rewarding" properties of nicotine, which serve to reinforce drug-seeking behaviour, are related to stimulation of the mesolimbic dopamine system of the brain. The critique focuses specifically on the evidence that many central nicotinic receptors, including those which mediate the effects of the drug on dopamine secretion, are readily desensitized by chronic exposure to agonist and that hypotheses which assume that nicotine inhaled from tobacco smoke invariably results in stimulation of the receptors must be treated with caution. Nicotinic receptors in the brain are, however, heterogeneous in nature with different molecular structures and pharmacologies. It is concluded that the reinforcing properties of nicotine sought by smokers may reflect both stimulation and desensitization of the different nicotinic receptor populations, and that smokers may adjust their smoking habits to achieve the balance of receptor stimulation and desensitization which they find most reinforcing. It seems likely that the efficacy of the different nicotine formulations during the treatment of smoking cessation may also reflect their ability to stimulate or desensitize brain nicotinic receptors.

Increased desire to smoke during acute stress

Conditions which promote smoking urges, or desire to smoke, are believed to be important in maintaining smoking behaviour, yet little controlled research has examined acute situational factors which increase desire to smoke. In this study, 16 male and 16 female smokers either smoked or sham-smoked with an unlit cigarette after brief abstinence during two sessions, one involving a stressful computer task and the other a non-stress task. Desire to smoke was greater during the stress vs. non-stress task for sham-smokers (p less than 0.01). Furthermore, although smoking desire decreased markedly after smoking in the smoking smokers (p less than 0.001), even this group tended to report greater desire to smoke during stress (p less than 0.10). There were no differences between males and females. These findings indicate that exposure to stressors increases desire to smoke, and suggest that such situations may be influential in maintaining smoking behaviour in smokers not attempting to quit.

The neurobiology of tobacco addiction

The key property that makes nicotine addictive is an ability to support the drug-seeking behaviour that has been demonstrated in self-administration and place preference experiments. This reinforcing effect is complex, possibly involving subjective states of euphoria, cognitive enhancements, changed adaptation to stress, and relief from the nicotine withdrawal syndrome. The neural mechanisms, described here by Ian Stolerman and Mohammed Shoaib, include a primary action on central nicotinic acetylcholine receptors, associated with selective activation of the mesolimbic dopamine system that also mediates other sources of reinforcement. Structures such as the mesopontine tegmentum may also contribute to the reinforcing effect, whereas hippocampal and striatal regions seem to mediate other behavioural changes.

Effect of buspirone on cigarette withdrawal symptoms and short-term abstinence rates in a smokers clinic

This paper reports on a double blind trial of the effect of buspirone, 15 mg per day, on cigarette withdrawal symptoms and ability of smokers to maintain abstinence during treatment. A total of 61 smokers were randomly assigned to active or placebo conditions. They were maintained on their drug for 2 weeks prior to attempting abstinence and then for a further 4 weeks of abstinence. Subjects attended weekly group sessions of a psychological treatment programme. There was no evidence that the side effects in the active drug group were worse than those in the placebo group. Although there was no significant difference between active and placebo conditions on withdrawal symptoms, smokers in the active drug condition were more than twice as likely to maintain abstinence for the duration of the study than those in the placebo condition (47% versus 16%, chi square = 5.3, P less than 0.025). The results provide preliminary evidence for short-term efficacy of buspirone as an aid to smoking cessation at a low dose. They also provide evidence of a dissociation between withdrawal symptoms and successful abstinence.