A comparison of the psychological characteristics of smokers, ex-smokers, and nonsmokers

Increased Risky Choice and Reduced CHRNB2 Expression in Adult Male Rats Exposed to Nicotine Vapor

While the cognitive enhancing effects of nicotine use have been well documented, it has also been shown to impair decision making. The goal of this study was to determine if exposure to nicotine vapor increases risky decision making. The study also aims to investigate possible long-term effects of nicotine vapor exposure on the expression of genes coding for cholinergic and dopaminergic receptors in brain. Thirty-two adult male Sprague Dawley rats were exposed to 24 mg/mL nicotine vapor or vehicle control, immediately followed by testing in the probability discounting task for 10 consecutive days. Fifty-four days after the 10-day vapor exposure, animals were sacrificed and expression of genes coding for the α4 and β2 cholinergic receptor subunits, and dopamine D1 and D2 receptors, were analyzed using RT-PCR. Exposure to nicotine vapor caused an immediate and transient increase in risky choice. Analyses of gene expression identified significant reductions in CHRNB2 and DRD1 in the nucleus accumbens core and CHRNB2 and DRD2 in the medial prefrontal cortex of rats previously exposed to nicotine vapor, relative to vehicle controls. Results provide data on the negative cognitive effects of nicotine vapor exposure and identify cholinergic and dopaminergic mechanisms that may affected with repeated use.

Exposure to nicotine vapor produced by an electronic nicotine delivery system causes short-term increases in impulsive choice in adult male rats

INTRODUCTION

Traditional cigarette use influences cost-benefit decision making by promoting impulsive choice. However, the impact of exposure via electronic nicotine delivery systems on impulsive choice remains unclear. Hence, the present study examined the short- and long-term effects of nicotine vapor on impulsive choice.

METHODS

Twenty-four adult male rats were trained in the delay discounting task, to choose between small, immediate food rewards or large, delayed food rewards. After 24 days of training in the task, rats were exposed to vapor containing either 0, 12, or 24 mg/mL of nicotine, for ten days. To validate inhalation of nicotine vapor, serum cotinine levels were analyzed on exposure days 1, 5, and 10 using enzyme-linked immunosorbent assay (ELISA). Following vapor exposure, rats were retrained in the discounting task until rats displayed stable responding, and the effects of nicotine vapor on choice preference were assessed.

RESULTS

Rats exposed to 12 and 24 mg/mL nicotine vapor displayed higher serum cotinine levels than control rats exposed to 0 mg/mL vapor. There were no differences in impulsive choice between any vapor exposure groups when tested 15 days after exposure, across 6 days of stable responding, suggesting that nicotine vapor does not have long lasting effects on impulsive choice. Interestingly, a subsequent nicotine vapor challenge revealed short-term increases in impulsive choice immediately following a single exposure to 24 mg/mL nicotine vapor, relative to choice preference immediately following exposure to 0 mg/mL vapor.

CONCLUSIONS

These results suggest that exposure to nicotine vapor causes immediate, short-term increases in impulsive choice.

IMPLICATIONS

E-cigarette use is increasing at an alarming rate, particularly among adolescents and young adults. This is concerning given the lack of research into the effects of nicotine vapor exposure on the brain and behavior. The present study describes a viable rodent model of human e-cigarette use and suggest that exposure to nicotine vapor produces short-term increases in impulsive choice.

Individual and family correlates for cigarette smoking among Taiwanese college students

OBJECTIVE

This college-based questionnaire survey aimed to explore the individual, family, and peer correlates for cigarette smoking among first-year college students.

METHOD

The sample included 2918 first-year college students (males, 45.5%) recruited from a national university in Taiwan (participation rate, 79.1%). The participants reported on questions about various substances, attitudes toward substances, personality characteristics, psychopathology, suicidal behaviors, parenting style, family function and use of substances, and peer substance use.

RESULTS

There were 263 (9.0%; males, 70.6%) current smokers. Compared to nonsmokers, college smokers were more extraverted and neurotic, and showed less harm avoidance, and more novelty seeking in their personality. They had more hostile, somatic, depressive, paranoid, and psychotic symptoms in terms of psychopathology. Smokers were more likely to use other substances, and to have suicidal ideations, wishes, plans, and attempts. Smokers perceived lower family cohesion, less care from their fathers, and less overprotection from their mothers. They were more likely to have peers and family members who also smoked or used other substances. The most associated correlates were male sex, older age, other substance use, novelty seeking, suicidal ideation and attempts, sibling and peer substance use, a prosubstance attitude, and less maternal overprotection.

CONCLUSIONS

Our findings support the association of cigarette use in Taiwanese young adults with several individual, family, and peer factors identified in Western studies. Intervention in cigarette use should be multifaceted, by taking its correlates and the concurrent psychopathology, use of substances, and suicidality into consideration.

Cue-elicited negative affect in impulsive smokers

Impulsivity is associated with cigarette smoking, but the nature of this relationship and the mechanisms that maintain it are relatively unknown. The relationship has often been thought to reflect appetitive processes, but research suggests that an affective pathway exists as well. The present study tested the effect of impulsivity on affective responses to an environmental smoking cue. Adult smokers (N=62) were exposed to a neutral cue and a smoking cue in separate experimental sessions in a repeated-measures design. Mixed-effects regression analyses showed that larger postexposure increases in negative affect were associated with high scores on 2 facets of impulsivity: urgency, t(179)=6.16, p<.001, and sensation seeking, t(179)=4.75, p<.001. Heightened impulsivity was associated with lower levels of positive affect generally but not with positive affective responses to cue exposure. Findings provide support for the existence of a negative affective pathway linking impulsivity and cigarette smoking, and they suggest that this pathway may be specific to the urgency and sensation-seeking components of impulsivity.

Examining impulsivity as an endophenotype using a behavioral approach: a DRD2 TaqI A and DRD4 48-bp VNTR association study

Background

Research on the genetic basis for impulsivity has revealed an array of ambiguous findings. This may be a result of limitations to self-report assessments of impulsivity. Behavioral measures that assess more narrowly defined aspects of impulsivity may clarify genetic influences. This study examined the relationship between possession of the DRD2 TaqI A and DRD4 48 bp VNTR genetic polymorphisms and performance on a behavioral measure of impulsivity, the delay discounting task (DDT), and three traditional self-report measures.

Methods

195 individuals (42% male) were recruited from a university campus and were assessed in small group sessions using personal computers. Genotyping was conducted using previously established protocols. For the DRD2 TaqI A locus, individuals were designated as possessing at least one copy of the A1 allele (A1+) or not (A1-), and for the DRD4 48-bp VNTR locus, individuals were designated as having at least one long allele (7 repeats or longer, L+) or not (L-). Principal analyses used multiple univariate factorial 2 (A1+/A1-) × 2 (L+/L-) analyses of variance.

Results

A significant main effect of A1+ status on DDT performance was evident (p = .006) as well as a significant interaction effect (p = .006) between both genes. No other significant effects were evident on the self-report measures, with the exception of a trend toward an interaction effect on the Sensation Seeking Scale. Exploratory analyses suggested that the significant effects were not a function of population stratification or gender.

Discussion

These data suggest that the DRD2 TaqI A and DRD4 VNTR polymorphisms influence impulsivity as measured with a delay discounting task. Specifically, these findings suggest that an interaction between the functional effects of the two unlinked genotypes results in significant difference in the balance of mesolimbic dopaminergic activation relative to frontal-parietal activation. However, these findings are also the first in this area and must be replicated.

Conclusion

These findings suggest a meaningful interaction between the DRD2 TaqI A and DRD4 VNTR polymorphisms in the expression of impulsivity and provide initial support for the utility of using behavioral measures for clarifying genetic influences on impulsivity.

Measuring impulsivity and modeling its association with cigarette smoking

Two types of behavioral measure are primarily used to examine impulsivity in humans and animals: Go/No-go tasks to assess inhibition and relative preference tasks to assess delay aversion. Several examples of each type of task are described so that common cognitive processes and variables affecting performance can be identified. Data suggest that smokers are more impulsive on each of these impulsivity measures than nonsmokers. Several models can be proposed to account for this group difference: (a) the differences predate and, possibly, are causally related to the initiation of cigarette smoking; (b) higher levels of impulsivity are associated with continued smoking, either through an association with heightened positive subjective effects of nicotine or heightened negative effects of nicotine abstinence (withdrawal); (c) nicotine causes neuroadaptations that result in elevated impulsivity in smokers. Studies relating to each of these models are reviewed, and it is concluded that all three models may contribute to the observed higher levels of impulsivity in smokers. However, pertinent studies are limited and additional systematic research is needed.

Conscientiousness and health-related behaviors: a meta-analysis of the leading behavioral contributors to mortality

Previous research has established conscientiousness as a predictor of longevity (H. S. Friedman et al., 1993; L. R. Martin & H. S. Friedman, 2000). To better understand this relationship, the authors conducted a meta-analysis of conscientiousness-related traits and the leading behavioral contributors to mortality in the United States (tobacco use, diet and activity patterns, excessive alcohol use, violence, risky sexual behavior, risky driving, suicide, and drug use). Data sources were located by combining conscientiousness-related terms and relevant health-related behavior terms in database searches as well as by retrieving dissertations and requesting unpublished data from electronic mailing lists. The resulting database contained 194 studies that were quantitatively synthesized. Results showed that conscientiousness-related traits were negatively related to all risky health-related behaviors and positively related to all beneficial health-related behaviors. This study demonstrates the importance of conscientiousness' contribution to the health process through its relationship to health-related behaviors.

Impulsivity in smoking, nonsmoking, and ex-smoking alcoholics

The impulsivity levels were evaluated and compared in smoking, nonsmoking, and ex-smoking abstinent alcoholics (N=400) in a French alcohol detoxification center. Impulsivity was measured using the Barratt Impulsiveness Scale, French version (BIS 10). The BIS scores correlated inversely with age. Gender had no effect on impulsivity scores, while impulsivity was associated with smoking. Adding age as a covariate, however, eliminated or moderated the association, with three exceptions: (1) among males, heavy smokers were more impulsive than nonsmokers and medium smokers; (2) on the nonplanning subscale, heavy smokers were more impulsive than all other groups, and (3) current smokers were more impulsive than ex-smokers. Elevated impulsivity levels appear to be an obstacle to smoking cessation. In addition, stopping smoking may diminish impulsivity levels in alcoholics. Routine testing of impulsivity in current alcoholic smokers might predict who might successfully become an ex-smoker.

Psychosocial and personality differences in chippers and regular smokers

Tobacco chippers are an anomalous group of smokers who, while having smoked regularly for years, have avoided the clutches of nicotine dependence. In an attempt to better understand the factors associated with nondependent cigarette smoking, this paper describes a study in which matched groups of regular smokers, chippers, and nonsmokers were compared on a number of personality and psychosocial variables believed relevant to drug-seeking behavior. The strongest finding indicated that sensation seeking best discriminates among the three groups, with nonsmokers clearly viewing themselves as more socially inhibited and less interested in pursuing sensations relative to both regular smokers and chippers, both of whom evidenced comparable scores. Regular smokers evidenced less self-control, or restraint, and appeared more impulsive and unable to resist temptation, compared to chippers and nonsmokers. Surprisingly, none of the groups could be differentiated on the basis of perceived stress, coping, or social support. Even among the personality variables, however, the effect sizes were relatively small, indicating that these differences in personality cannot fully account for chipper's resistance to dependence.

Personality and cigarette smoking in Italy, Poland, and the United States

This study reports data on over 700 young adults, undergraduate and medical students attending the University of Vermont, the University of Rome, and the Warsaw Medical Academy. Each subject provided information about cigarette smoking history and completed several personality, Type A, and life events inventories. Subjects were classified as nonsmoker, ex-smoker, and smoker. Each measure was analyzed by ANOVA on this basis, with gender and country as additional main effects. Smokers were found to have higher state anxiety, a lower lie score, and were more Type A than ex-smokers and nonsmokers, but they tended to report fewer life events and of lower value.