Personality differences related to smoking and adult attention deficit hyperactivity disorder

Tridimensional Personality Questionnaire (TPQ) scores are compared for three groups of adults: (a) current smokers with Attention Deficit Hyperactivity Disorder (ADHDSmk, n = 14); (b) current smokers without ADHD (NonADHDSmk, n = 21); and (c) ADHD never smokers (ADHDNevSmk, n = 17). The ADHASmk participants started smoking at a significantly younger age than NonADHDSmk participants. On the TPQ Novelty Seeking (NS) scale, all groups scored more than a standard deviation above the norm, and ADHDSmk participants scored significantly higher than NonADHDSmk participants. The earlier onset of smoking in ADHD adults suggests that smoking prevention efforts may be particularly important for ADHD children. Previous studies have reported that both smokers and ADHD patients have elevated NS scores; this study suggests an additive effect for smokers with ADHD. This exaggerated tendency towards thrill seeking in ADHDSmk participants may complicate smoking-cessation treatment in this population, because the health consequences of smoking may be of less concern to ADHD smokers.

Individual differences in sensitivity to nicotine: implications for genetic research on nicotine dependence

Recent evidence suggests that cigarette smoking has a heritability index around 53%. While related research on underlying mechanisms also supports the idea that genetic factors contribute to nicotine dependence--as well as to cofactors such as substance use and mood disorders--the nature of the behavioral traits and biological capacity for reinforcement that constitutes vulnerability to nicotine dependence is not well understood. The present review explores the problem of why some people become highly nicotine dependent, others develop a pattern of occasional use, and still others avoid the drug entirely despite extensive exposure and widespread experimentation with tobacco in the population. Recent research--both infrahuman and human--suggests that vulnerability to nicotine dependence is related to high initial sensitivity to nicotine and that the development of tolerance is more rapid and self-administration more extensive in such individuals. Relevant findings from neuroscience and biobehavioral research are reviewed in order to identify variables and methodologies that might improve the reliability and validity of behavioral and molecular genetic studies on cigarette smoking. The integration of research in these areas may lead to new insights in the understanding of nicotine dependence as well as to improved techniques for prevention and treatment.

Cigarette smoking in adult patients diagnosed with attention deficit hyperactivity disorder

Previous work has shown that adolescent hyperactivity patients are significantly more likely to smoke than controls. To determine whether this pattern persists in adults, we studied a series of 71 patients (55 males, 16 females; mean age +/- SD: 33.9 +/- 11.4 years) diagnosed with ADHD. Of the males, 23 (42%) were current smokers, 7 (13%) were ex-smokers, and 25 (45%) were never smokers. Comparable figures for males in the general population in 1991, unselected for ADHD, were 28.1%, 29.1%, and 42.1%, respectively. Of the females, 6 (38%) were current smokers, 5 (31%) were ex-smokers, and 5 (31%) had never smoked, as compared with 23.5%, 19.0%, and 57.6%, respectively, in the general population. Quit ratio (percentage of ever-smokers who were ex-smokers) was 29% for ADHD patients, compared with 48.5% in the general population. The discrepancy was accounted for by the males, whose quit ratio was 23%, compared with 51.6% in the general population; the figure for ADHD females (45%) was similar to that in the general population (44.7%). Smokers recalled experiencing a significantly higher number of ADHD symptoms (11.5 +/- 1.7) as children than never smokers (9.9 +/- 2.3; p < .01) and scored significantly higher on several indices of childhood and adult comorbidity. Our findings suggest that ADHD patients overinclude smokers, and that these smokers find it extremely difficult to quit. For ADHD smokers, smoking may have begun as an attempt to manage deficits in attention and concentration, as suggested by greater childhood symptomatology in these patients.

Effects of nicotine abstinence and menstrual phase on task performance

Both menstrual phase and nicotine have been shown to affect task performance. Though conflicting results have been reported, at least one well-controlled study has demonstrated that women at midluteal phase show superior performance on speech articulation and speeded motor coordination tests, but poorer performance on perceptual-spatial tests, than during menses. Smokers have demonstrated superior performance on numerous tasks following nicotine than following placebo. To explore the separate and combined influence of these factors, we studied 13 regularly-menstruating smokers using a two (smoking vs. 12 hours' abstinence) by two (menstrual vs. midluteal phase) factorial design. During each session, subjects completed a test battery including two speeded motor coordination tasks, a computerized reaction time test, and the Stroop (1935) color/word test. Subjects completed the Stroop color and color-word tasks significantly faster after ad lib smoking than after overnight abstinence. No other significant differences emerged. Our findings replicate, in an all-female sample, previous reports that speed of cognitive processing is reduced by nicotine abstinence (or enhanced by nicotine administration). Our failure to observe menstrual cycle effects raises the possibility that the anti-estrogenic effects of smoking may attenuate phase differences in performance.

Pharmacological and non-pharmacological smoking motives: a replication and extension

Cigarette smokers (n = 387) completed a questionnaire measure of smoking motives, and subgroups of this sample provided external validation information. Seven factors emerged from a principal components' analysis: automatic, sedative, addictive, stimulation, psychosocial, indulgent and sensorimotor manipulation. A higher-order principal components analysis revealed the presence of two second-order factors. Inspection of the pattern of correlations between factor scores and criterion variables clearly indicated that the first four factors above and their underlying second-order factor are more closely related to nicotine pharmacology and mood-altering effects of nicotine than the latter three motives and their underlying second-order factor. Moreover, the positive correlations between these pharmacological motives and age, coupled with a negative relationship between age and the non-pharmacological motives, support the description of the smoking career as a progressive transfer of reward from non-pharmacological to pharmacological factors. These findings suggest that self-reported reasons for smoking represent more than bias in verbal report.

Why some people smoke and others do not: new perspectives

Because initial reinforcement consequences set the stage for subsequent nicotine use, elucidation of the contribution of environmental and inherited factors is crucial to an understanding of nicotine dependence as well as of individual differences in susceptibility to cigarette smoking. A review of some recent animal research and laboratory studies of smokers and never-smokers suggests that vulnerability to nicotine dependence is related to high initial sensitivity to nicotine and that the development of acute pharmacodynamic tolerance in these individuals--particularly to effects of nicotine that are toxic or aversive--may be an adaptation for protecting homeostasis.

Effects of menstrual phase on nicotine, alcohol, and caffeine intake in smokers

To determine whether cigarette smoking and other drug use are affected by menstrual phase, daily diaries rating menstrual symptomatology, smoking, and alcohol and caffeine intake in female smokers were examined. Women with premenstrual symptomatology were excluded. Menstrual symptomatology peaked during menses and was accounted for primarily by symptoms indicative of physical discomfort. Smoking did not differ as a function of menstrual phase, nor did there emerge any systematic intrasubject correlation between symptomatology and smoking. Alcohol and caffeine intake also failed to show phase-related differences. It was concluded that substance intake is highly stable across the menstrual cycle in female smokers.

Reliability of the Fagerstrom Tolerance Questionnaire and the Fagerstrom Test for Nicotine Dependence

The purpose of this study was to assess the test-retest stability of the Fagerstrom Tolerance Questionnaire (FTQ) in two samples: (a) paid subjects in an American laboratory; data were collected via telephone screen and subsequently via questions embedded in a written history; and (b) smokers hospitalized for depression in Paris; data were collected via a written questionnaire upon admission and again after 3 weeks of treatment for depression. Reliability data are also presented for a recently revised version of the FTQ, the Fagerstrom Test for Nicotine Dependence (FTND), and compared with FTQ data collected in a subsample of subjects in the American database who received both versions of the questionnaire. Both the FTQ (in both samples) and the FTND proved to be highly reliable. The validity of the scales, using cotinine, number of years smoked, and the "addictive" factor on the Classification of Smoking by Motives questionnaire as criterion variables, was also supported. No relationship between FTQ score and severity of depression was detected in either sample. Internal consistency was somewhat higher for the FTND than for the FTQ, replicating previous findings in the literature.

Gender differences in prospectively versus retrospectively assessed smoking withdrawal symptoms

Investigations of gender differences in the frequency and/or intensity of smoking withdrawal symptomatology have yielded conflicting findings. Several studies using measures collected both before abstinence and at the peak of symptomatology have failed to find gender differences. Yet, when asked to rate symptomatology experienced during past quit attempts, women have repeatedly been shown to endorse significantly more symptomatology than men. A possible explanation is that, although men and women show no differences when rating symptoms prospectively, women remember their past withdrawal symptoms as being more severe than do men, either because women exaggerate the difficulties they experience or because men downplay them. To test this hypothesis, and to determine whether men or women were more accurate in their recollections, we combined data from two studies in which subjects were asked to assess symptoms prospectively following 2 days of abstinence, and also to rate withdrawal during past quit attempts. As predicted, we found the effects of abstinence to be similar when assessed prospectively but different when assessed retrospectively, with women reporting more symptomatology than men. Men whose retrospective and prospective responses were discordant consistently underestimated the likelihood of experiencing symptomatology; women showed no consistent trends. The total number of symptoms reported retrospectively by women was similar to the total number reported prospectively, whereas men significantly underestimated the number of symptoms that they actually experienced. These findings may suggest ways in which treatment strategies can be tailored to the differences between male and female styles in recalling past experiences with abstinence from smoking.

Alexithymia and negative affect: relationship to cigarette smoking, nicotine dependence, and smoking cessation

Alexithymia is associated with substance abuse and may interfere with successful psychotherapy. Alexithymia's relation to smoking, nicotine dependence, and smoking cessation therapy is unknown, and potentially overlaps with negative affect. Three studies addressed the relations between alexithymia, negative affect, and smoking. In Study 1, 67 young adult smokers were more depressed than 370 past or never smokers, but no different on the Toronto Alexithymia Scale total or subscale scores. In Study 2, negative affect--but not alexithymia--was related to greater nicotine dependence among 99 chronic smokers. In Study 3, alexithymia tended to predict increased patient participation in cognitive-behavioral therapy for smoking; low nicotine dependence--but neither alexithymia nor negative affect--predicted abstinence from smoking at treatment end. Alexithymia appears to be independent of negative affect and unrelated to cigarette smoking or nicotine dependence, suggesting that the affect regulation deficits in alexithymia play a negligible role in nicotine addiction.

Why some people smoke and others do not: new perspectives

Because initial reinforcement consequences set the stage for subsequent nicotine use, elucidation of the contribution of environmental and inherited factors is crucial to an understanding of nicotine dependence as well as of individual differences in susceptibility to cigarette smoking. A review of some recent animal research and laboratory studies of smokers and never-smokers suggests that vulnerability to nicotine dependence is related to high initial sensitivity to nicotine and that the development of acute pharmacodynamic tolerance in these individuals--particularly to effects of nicotine that are toxic or aversive--may be an adaptation for protecting homeostasis.

Differences between smokers and never-smokers in sensitivity to nicotine: a preliminary report

Sensitivity to nicotine was explored using test doses administered via intra-nasal aerosol in 10 smokers and 10 never-smokers. Smokers received 1.50 mg nicotine (in 2 sprays, < 5 seconds apart, one spray per nostril); never-smokers received either 0.50 mg (n = 3) or 0.25 mg (n = 7) nicotine. Accumulation of nicotine in plasma, per unit dose administered, was nearly four times greater in never-smokers than in smokers, indicating differences in pharmacokinetic tolerance. To examine sensitivity to nicotine without this confound, peak physiological reactivity (heart rate and blood pressure changes) was divided by peak plasma nicotine increment and the ratio was expressed as a function of cotinine level prior to dosing, thereby relating sensitivity to nicotine to history of exposure. In smokers, functional sensitivity to nicotine was inversely related to customary nicotine intake, replicating previous findings for light and heavy smokers. The observation that never-smokers were not much more sensitive to nicotine than light smokers is notable given the disparity in previous history of exposure.

Temporal stability and within-subject consistency of nicotine withdrawal symptoms

This study tested the temporal stability and within-subject consistency of the Diagnostic and Statistical Manual-III-R (DSM-III-R) nicotine withdrawal symptoms in 39 (21 female, 18 male) regular smokers. Subjects provided withdrawal symptom ratings while smoking ad libitum and during two 48-hour abstinence periods that were separated by 1 week. All but two symptoms, increased eating and hunger, demonstrated adequate temporal stability (i.e., stability coefficients > or = .70). Within-subject consistency was found for impatience, anxiety, difficulty concentrating, and irritability. The total (average) score emerged as the most stable and consistent indicator of withdrawal. Results of a cluster analysis suggest the presence of two groups of smokers based on the withdrawal experience. Possible reasons for variability in nicotine withdrawal symptom reports are discussed.

The female weight-control smoker: a profile

Hypothesizing the existence of a subgroup of female smokers for whom nicotine masks, and abstinence unmasks, a tendency toward hyperphagia and perhaps even subthreshold disordered eating, we compared female "weight-control smokers" (WC; n = 46) and "non-weight-control smokers" (NWC; n = 52) on smoking- and eating-related variables. We also examined the relationship between weight-control smoking and withdrawal symptomatology during 48-hours of nicotine abstinence (n = 23). Although WC were not more depressed, anxious, or nicotine-dependent than NWC, they were significantly more likely to report weight gain and increased hunger during abstinence; they also scored higher on Cognitive Restraint and Disinhibition (Three-Factor Eating Questionnaire). The expected correlation of cotinine with weight emerged for NWC but not for WC. Weight-control smoking correlated with increased eating during abstinence. Our findings suggest that WC use dietary restraint as well as smoking to manage weight, and that abstinence may precipitate episodes of disinhibited or binge eating. If WC overinclude women vulnerable to excess or unpredictable eating and consequently to substantial weight gain that can be managed by nicotine, highly focused treatment strategies may be helpful.

The effects of menstrual phase and nicotine abstinence on nicotine intake and on biochemical and subjective measures in women smokers: a preliminary report

Nicotine intake, menstrual and smoking withdrawal symptomatology, and baseline cortisol and MHPG were assessed in nine women smokers under conditions of ad lib smoking and overnight abstinence in three menstrual phases (early follicular, mid-to-late follicular, and late luteal). A trend towards higher nicotine intake (p < 0.10) was observed in the mid-to-late follicular phase. Although menstrual symptomatology was not significantly elevated during the smoking abstinence condition overall, abstinence appeared to prevent the normal reduction in symptomatology during the mid-to-late follicular phase that occurred under conditions of ad lib smoking. Menstrual and withdrawal symptoms were highly correlated, and both were most pronounced during the late luteal/abstinence condition. The smoking-specific item "craving" reflected this pattern, though in attenuated form, suggesting that the observed exacerbation of withdrawal symptomatology was not simply due to generalized dysphoria, as queried in both instruments. MHPG was significantly elevated in the late luteal phase, whereas cortisol was significantly higher during ad lib smoking than during abstinence and tended to be highest in the mid-to-late follicular phase. Further investigation will be needed to determine the functional significance of these findings for understanding and treating smoking in women.

Nicotine and the central nervous system: biobehavioral effects of cigarette smoking

The effects of nicotine, like those of other drugs with potential for abuse and dependence, are centrally mediated. The impact of nicotine on the central nervous system is neuroregulatory in nature, affecting biochemical and physiological functions in a manner that reinforces drug-taking behavior. Dose-dependent neurotransmitter and neuroendocrine effects occur as plasma nicotine levels rise when a cigarette is smoked. Circulating levels of norepinephrine and epinephrine increase, and the bioavailability of dopamine is altered as well. Among the neuroendocrine effects are release of arginine vasopressin, beta-endorphin, adrenocorticotropic hormone, and cortisol. Notably, several of these neurochemicals are psychoactive and/or known to modulate behavior. Thus, affective states or cognitive demands may be favorably modified (at least temporarily) by nicotine intake. When nicotine is inhaled, the neuroregulatory effects just described are immediately available and the reinforcing effects of the drug are maximized. On the other hand, nicotine gum and most other nicotine replacement vehicles in current use have a slower onset of action, resulting in less reinforcement value. Recent data suggest that smoking cessation rates may be optimized by tailoring the dose of nicotine replacement (for example, 2 or 5 mg of nicotine gum) to the individual degree of nicotine dependence. In view of the dynamic interactions between the neuroregulatory effects of nicotine and a host of environmental conditions, nicotine replacement therapy is best carried out in combination with behavior modification techniques.

National working conference on smoking and body weight. Task Force 1: Mechanisms relevant to the relations between cigarette smoking and body weight

Careful, comprehensive, and empirical observations provide the building blocks of the sciences, whereas theory and mechanisms provide the "cement" to hold the blocks together and serve as blueprints to direct future building. This article resulted from several days of discussion regarding theories that may underlie the relation between cigarette smoking and body weight and the relation between smoking cessation and body weight. The working group composed of social and biological scientists who addressed this assignment considered what is already known within the smoking and body weight literature and also considered relevant findings from studies of smoking or body weight regulation that have not directly addressed the interaction of these variables. As expected, we were successful at listing some of what is not known and what is worth knowing. We also tried to identify fruitful possibilities for research activity that might clarify mechanisms of action and eventually lead to theoretical development. Because we do not believe that the present state of our deliberations merits the label of theories, we decided, instead, to report the summary of these deliberations as potential mechanisms relevant to the relation between smoking and body weight.

Cotinine in an ultrafiltrate of saliva

BACKGROUND

We have developed a device for the simplified collection of a prepurified sample of saliva in the mouth.

METHOD

The device is based on the principle of an osmotic pump and accumulated about 1.2 ml of an ultrafiltrate of saliva within 8 min. We have investigated the ultrafiltrate for its utility as a biological medium in the evaluation of cigarette smoking status.

RESULTS

(a) In 58 matched samples from 13 subjects, the correlation coefficient for the cotinine concentration in the saliva and the ultrafiltrate was 0.95; (b) in matched plasma and ultrafiltrate samples from 27 smokers, the correlation coefficient for the cotinine concentrations was 0.96 with plasma containing 1.2 times the ultrafiltrate mean; (c) in a nonsmoker, elevated cotinine levels could be detected in the ultrafiltrate more than 24 hr after smoking 2 cigarettes, and the pattern of rise and decrease reflected that in whole saliva; and (d) in a habitual smoker; the mean cotinine concentration in the ultrafiltrate was 157 ng/ml (SD +/- 25.7 ng/ml) during a period of smoking 15 cigarettes per day and dropped to a mean of 47 ng/ml (SD +/- 10.5) when smoking was reduced to 5 cigarettes per day; after cessation of smoking, detectable concentrations of cotinine persisted for up to 5 days.

CONCLUSION

The device facilitated the aesthetic, noninvasive collection of a biological sample useful in the validation of smoking status.

Euphoriant effects of nicotine in smokers

Two studies were conducted to replicate and extend previous demonstrations of smoking-induced, dose-related reports of euphoria, and to confirm this relationship using measures of plasma nicotine. In experiment 1, overnight-deprived subjects, in three different sessions, smoked ultralow-, high-nicotine, and usual-brand cigarettes. In experiment 2, ultralow-, medium-, and high-nicotine cigarettes were used, and plasma nicotine was measured. In both studies, subjects were asked to depress a button during euphoric sensations. Number of sensations for the ultralow-nicotine cigarette was significantly lower than for the high-nicotine cigarette in the first study, and than for both the medium- and high-nicotine conditions in the second; a significant linear trend was observed for number of sensations as a function of plasma nicotine level in the second study. For the high-nicotine cigarette, 19 of 22 subjects experienced at least one sensation (mean around three), starting around 2.5 min after lighting up. Together, these studies support the existence of a dose-response relationship for nicotine-induced euphoric sensations; suggest that they are more pronounced following overnight abstinence than following minimal deprivation, and in more dependent smokers; and characterize in detail the temporal features of these sensations.

Controlled dosing of nicotine via an Intranasal Nicotine Aerosol Delivery Device (INADD)

The present report describes an Intranasal Nicotine Aerosol Delivery Device (INADD) employing an artist's airbrush as aerosolizer and precise, electromechanical control of spray duration. It was designed for the administration of controlled doses of nicotine in a laboratory setting and has been used successfully in over 30 smokers and nonsmokers of both genders. In the present study, nicotine was administered to 12 male smokers at three different doses (0.05 mg, 1.00 mg, and 2.00 mg), and at the same dose (1 mg) on three different occasions. The low dose produced a minimal change in plasma nicotine, while the high dose produced a peak increment of around 16 ng/ml. The medium dose reliably produced a peak increment of around 8-9 ng/ml on all three occasions. Nicotine in plasma showed a sharp rise followed by a slower decline, mimicking the pattern associated with cigarette smoking. Physiological and biochemical responses showed significant dose-response relationships. Subjective reports suggested that aerosol dosing was somewhat aversive, but it is unclear whether this effect is intrinsic to the method or due to other factors. The device described in this report answers the need for a safe and easy means of controlling nicotine dose. Moreover, since nicotine administration via aerosol is novel for both smokers and non-smokers, minimizing the contributions of behavioral tolerance and habituation to the dosing vehicle, it lends itself to the comparison of the pharmacological effects of nicotine between experienced and naive subjects.

Relationship of Tridimensional Personality Questionnaire scores and smoking variables in female and male smokers

The Tridimensional Personality Questionnaire (TPQ) was developed by Cloninger (1986) to measure heritable variation in three patterns of response to environmental stimuli: novelty seeking, harm avoidance, and reward dependence. Cloninger (1987) used the TPQ to identify two types of alcoholism: Type 1 (low novelty seeking, high harm avoidance and reward dependence; both male and female) and Type 2 (high novelty seeking, low harm avoidance and reward dependence; predominantly male). To determine whether characteristic patterns exist in smokers, we administered the TPQ to 119 female and 121 male smokers, along with the Fagerstrom Tolerance Questionnaire (FTQ, a measure of nicotine dependence), the Russell Motives for Smoking Questionnaire (RMSQ), and the Spielberger State-Trait Anxiety Inventory (STAI/trait). Compared with a normative sample, our sample exhibited elevated scores on the Novelty-Seeking scale; female smokers were somewhat overrepresented in the highest quartile of the Harm-Avoidance scale; both genders tended to be clustered in the lower quartiles of the Sentimentality-Attachment-Dependence subscale of the Reward-Dependence scale and in the highest quartile of the Persistence subscale. Female smokers showed a significant positive association between Harm Avoidance and FTQ scores, and Harm Avoidance was positively correlated with several RMSQ factors (including Additive smoking) in both genders. These findings suggest that the likelihood of becoming a smoker may be a function of novelty seeking and reward dependence, whereas degree of dependence or addiction once the habit is entrained may be linked to harm avoidance. Our observations establish the potential utility of the TPQ as a tool for examining environmental and heritable variation in smoking behavior and may contribute to improved strategies for prevention and treatment of smoking.

Sweet taste preference in women smokers: comparison with nonsmokers and effects of menstrual phase and nicotine abstinence

Cigarette smokers weigh less than comparably aged nonsmokers, and many gain weight following cessation. Though some evidence suggests that nicotine reduces food intake, with a selective effect on sweet-tasting foods, the issue remains unresolved. In the current study, 64 women (20 smokers, 26 never-smokers, and 18 ex-smokers) were tested for sweet taste preference; 9 of these smokers were studied under conditions of both ad lib smoking and overnight abstinence, in three hormonally verified menstrual phases. 1) Although no overall differences were detected in taste preference among the three groups, significantly more smokers than nonsmokers preferred the higher sucrose concentrations. 2) No significant differences due to menstrual phase were observed. 3) Although preference ratings did not differ significantly between overnight abstinence and ad lib smoking, a subset of smokers who preferred higher sucrose concentrations rated their preference for the solutions significantly higher during the ad lib smoking sessions. Our findings suggest that smoking and nonsmoking women differ with respect to taste preference and that, at least in a subset of female smokers, preference is affected by nicotine abstinence/acute dosing.

Biobehavioral research on nicotine use in women

More American women are taking up smoking than men and fewer are quitting; if current trends continue, rates for women will surpass those for men by the mid-1990's. But ironically, much of what is known about the biobehavioural aspects of smoking is based on research using male subjects. The present paper reviews evidence suggesting that: (1) women may differ from men with regard to nicotine intake and/or effects; (2) nicotine intake and effects may be influenced by menstrual cycle phase; (3) oral contraceptive use and estrogen replacement therapy may affect intake and effects of nicotine; (4) the effects of chronic nicotine use on female reproductive endocrinology may have implications for the reinforcement of smoking; and (5) pharmacological agents used to treat smoking may have different effects in women than in men. Guidelines and suggestions are presented by future biobehavioural research in women, including standardization of assessment procedures, attention to the use of appropriate controls, and use of pharmacological probes.

Research on stress and smoking: progress and problems

Despite evidence that smoking behaviour increases in the context of stress, there has yet to be a clear-cut demonstration that nicotine intake is similarly enhanced. Although nicotine intake has been shown to reduce reported anxiety in the context of stress, the controlling conditions (type of stressor, intensity, temporal relationships, etc.) need further exploration. Recent findings involving nicotine's effects on the hypophyseal-adrenal axis provide a new perspective on these issues, in that increased nicotine intake during exposure to a stressor may represent, at least in part, behavioral compensation for diminished sensitivity to nicotine brought about by nicotine-stimulated corticosteroid release. Corticosteroids may decrease central nervous system excitability in a way that could account for anxiety reduction; on the other hand, anxiety reduction may be an epiphenomenon with respect to the reinforcement of smoking behaviour. The integration of behavioural, physiological, and biochemical research exemplified by the above approach should lead to a better understanding of stress and smoking.