Personality and the inheritance of smoking behavior: a genetic perspective

The Outcome of Pregnancy Among Tobacco Users in Tertiary Care Hospital of Chhattisgarh Province of India

BACKGROUND

Tobacco use is responsible for numerous adverse pregnancy outcomes for females and their infants. The aim of this study was to explore the adverse outcome of tobacco use among pregnant females.

METHOD

 A cross-sectional study was conducted on 1250 females in the third trimester of pregnancy from April to June 2022, which were exposed to tobacco use in the form of gudaku, tobacco chewing, gutka, or smoking. Complications and outcomes during and after pregnancy were recorded based on self-administered questionnaires. Statistical analysis was performed using the Statistical Package for Social Sciences (SPSS) (IBM SPSS Statistics, Armonk, NY) software version 20.0 for categorical data, frequencies (n) and percentages (%) were calculated, and the chi-square test was used for determining intergroup differences.

RESULTS

 Out of 1250 females, tobacco exposure was present among 429 (34.3%), and 821 (65.7%) had no tobacco exposure. Of 429, 36.10% of females complained about complications such as abortion (1.60%), antepartum hemorrhage (0.90%), congenital anomaly (0.20%), infertility (1.20%), intrauterine fetal death (IUFD) (0.50%), intrauterine growth restriction (IUGR) (0.90%), oligohydramnios (OLIGO) (3.30%), preterm labor (18.40%), premature rupture of membrane (6.30%), and anemia (2.80%), which were slightly higher than the females with no tobacco exposure. In tobacco users, obstructive complications were found to be significant with a p value of 0.0036.

CONCLUSION

Our study concluded that tobacco use could have an adverse effect on their fetus and infants, as well as the pregnant females themselves. Policymakers need to ensure effective strategies that pregnant females, their partners, and close relatives need to have enough knowledge to avoid potential risks.

Association of genetic liability to smoking initiation with e-cigarette use in young adults: A cohort study

BACKGROUND

Tobacco smoking and e-cigarette use are strongly associated, but it is currently unclear whether this association is causal, or due to shared factors that influence both behaviours such as a shared genetic liability. The aim of this study was to investigate whether polygenic risk scores (PRS) for smoking initiation are associated with ever use of e-cigarettes.

METHODS AND FINDINGS

Smoking initiation PRS were calculated for young adults (N = 7,859, mean age = 24 years, 51% male) of European ancestry in the Avon Longitudinal Study of Parents and Children, a prospective birth cohort study initiated in 1991. PRS were calculated using the GWAS & Sequencing Consortium of Alcohol and Nicotine use (GSCAN) summary statistics. Five thresholds ranging from 5 × 10-8 to 0.5 were used to calculate 5 PRS for each individual. Using logistic regression, we investigated the association between smoking initiation PRS and the main outcome, self-reported e-cigarette use (n = 2,894, measured between 2016 and 2017), as well as self-reported smoking initiation and 8 negative control outcomes (socioeconomic position at birth, externalising disorders in childhood, and risk-taking in young adulthood). A total of 878 young adults (30%) had ever used e-cigarettes at 24 years, and 150 (5%) were regular e-cigarette users at 24 years. We observed positive associations of similar magnitude between smoking initiation PRS (created using the p < 5 × 10-8 threshold) and both smoking initiation (odds ratio (OR) = 1.29, 95% CI 1.19 to 1.39, p < 0.001) and ever e-cigarette use (OR = 1.24, 95% CI 1.14 to 1.34, p < 0.001) by the age of 24 years, indicating that a genetic predisposition to smoking initiation is associated with an increased risk of using e-cigarettes. At lower p-value thresholds, we observed an association between smoking initiation PRS and ever e-cigarette use among never smokers. We also found evidence of associations between smoking initiation PRS and some negative control outcomes, particularly when less stringent p-value thresholds were used to create the PRS, but also at the strictest threshold (e.g., gambling, number of sexual partners, conduct disorder at 7 years, and parental socioeconomic position at birth). However, this study is limited by the relatively small sample size and potential for collider bias.

CONCLUSIONS

Our results indicate that there may be a shared genetic aetiology between smoking and e-cigarette use, and also with socioeconomic position, externalising disorders in childhood, and risky behaviour more generally. This indicates that there may be a common genetic vulnerability to both smoking and e-cigarette use, which may reflect a broad risk-taking phenotype.

Emotional and Affective Temperaments in Smoking Candidates for Bariatric Surgery

INTRODUCTION

The prevalence of smoking habits in severe obesity is higher than in the general population. There is some evidence that smokers have different temperaments compared to non-smokers. The aim of this study is to evaluate the associations between smoking status (smokers, ex-smokers and non-smokers) and temperament characteristics in bariatric surgery candidates.

METHODS

We analyzed data on temperament of 420 bariatric surgery candidates, as assessed by the AFECTS scale, in an exploratory cross-sectional survey of bariatric surgery candidates who have been grouped into smokers, ex-smokers and non-smokers.

RESULTS

We detected significant statistical differences in temperament related to the smoking status in this population after controlling the current use of psychiatric medication. Smokers had higher anxiety and lower control than non-smokers. Ex-smokers with BMI >50 kg/m(2) presented higher coping and control characteristics than smokers.

CONCLUSIONS

Smoking in bariatric surgery candidates was associated with lower control and higher anxious temperament, when controlled by current use of psychiatric medication. Smokers with BMI >50 kg/m(2) presented lower coping and control than ex-smokers. Assessment of temperament in bariatric surgery candidates may help in decisions about smoking cessation treatment and prevention of smoking relapse after surgery.

Natural genetic variability of the neuronal nicotinic acetylcholine receptor subunit genes in mice: Consequences and confounds

Recent human genetic studies have identified genetic variants in multiple nicotinic acetylcholine receptor (nAChR) subunit genes that are associated with risk for nicotine dependence and other smoking-related measures. Genetic variability also exists in the nAChR subunit genes in mice. Most studies on mouse nAChR subunit gene variability to date have focused on Chrna4, the gene that encodes the α4 nAChR subunit and Chrna7, the gene that encodes the α7 nAChR subunit. However, genetic variability exists for all nAChR genes in mice. In this review, we will describe what is known about nAChR subunit gene polymorphisms in mice and how it relates to variability in nAChR expression and function in brain. The relationship between nAChR genetic variability in mice and the effects of nicotine on several behavioral and physiological measures also will be discussed. In addition, an overview of the contribution of other genetic variation to nicotine sensitivity in mice will be provided. Finally, the potential for natural genetic variability to confound and/or modify the results of studies that utilize genetically engineered mice will be considered. As an example of the ability of a natural genetic variant to modify the effect of an engineered mutation, data will be presented that demonstrate that the effect of Chrna5 deletion on oral nicotine intake is dependent upon naturally occurring variant alleles of Chrna4. This article is part of the Special Issue entitled 'The Nicotinic Acetylcholine Receptor: From Molecular Biology to Cognition'.

A genetic variant in CHRNB3-CHRNA6 increases risk of esophageal squamous cell carcinoma in Chinese populations

Nicotinic acetylcholine receptors are important regulators of smoking behavior and tobacco carcinogenesis. We studied the association of the CHRNB3-A6 variant rs13280604 in relation to esophageal squamous cell carcinoma (ESCC) in Chinese populations. Two independent case-control studies were conducted. The first case-control study, consisted of 866 ESCC patients and 1621 healthy controls from Northern China, and the second case-control study consisted of 853 ESCC patients and 860 unrelated controls from Southern China. A logistic regression model was used to evaluate the associations of rs13280604 with cancer risk. We found that Rs13280604 GG/AG genotypes were significantly associated with increased risk for ESCC in both case-control studies from Northern [odds ratio (OR), 1.42, 95% confidence interval (CI), 1.19-1.70, P = 1.1×10(-4)], Southern China (OR, 1.56, 95% CI, 1.26-1.93, P = 5.2×10(-5)), and the combined population of both studies (OR, 1.44, 95% CI, 1.26-1.65, P = 8.7×10(-8)), respectively. Our results suggest that this CHRNB3-A6 variant confers susceptibility to ESCC risk. However, future larger studies are needed to validate our finding.

Ethnic-specific genetic association of variants in the corticotropin-releasing hormone receptor 1 gene with nicotine dependence

Twin and family studies indicate that smoking addiction is highly influenced by genetic factors. Variants in the corticotropin-releasing hormone receptor 1 (CRHR1) gene have been associated with alcoholism and depression. In this study, we tested five single nucleotide polymorphisms (SNPs) in CRHR1 for their association with ND, which was assessed by smoking quantity (SQ), the Heaviness of Smoking Index (HSI), and the Fagerström test for ND (FTND) in 2,037 subjects from 602 families of either European American (EA) or African American (AA) ancestry. Association analysis of the five SNPs revealed a significant association of rs171440 with SQ in the AA sample and with SQ and FTND in the pooled AA and EA samples. Haplotype-based association analysis indicated significant association of haplotypes C-C (56.9%) and T-C (38.9%), formed by SNPs rs171440 and rs1396862, with SQ in the AA sample, C-C-G (47.6%) with SQ, and T-C-G (42.3%), formed by SNPs rs171440, rs1396862, and rs878886, with SQ and FTND in the pooled AA and EA samples. However, none of these associations remained significant after correction for multiple testing. Together, our results provide suggestive evidence for the involvement of CRHR1 in ND, which warrants further investigation using larger independent samples.

Association between genetic variants on chromosome 15q25 locus and several nicotine dependence traits in Polish population: a case-control study

Tobacco smoking continues to be a leading cause of disease and mortality. Recent research has confirmed the important role of nicotinic acetylcholine receptor (nAChR) gene cluster on chromosome 15q 24-25 in nicotine dependence and smoking. In this study we tested the association of smoking initiation, age at onset of daily smoking, and heaviness of smoking with five single nucleotide polymorphisms (SNPs) within the CHRNA5-CHRNA3-CHRNB4 cluster. The group of 389 adult subjects of European ancestry from the north of Poland, including 212 ever (140 current and 72 former) and 177 never smokers with mean age 49.26, was genotyped for rs16969868, rs1051730, rs588765, rs6495308, and rs578776 polymorphisms. Distributions of genotypes for rs16969868 and rs1051730 were identical so they were analyzed together. Further analysis revealed the association between rs16969868-1051730 (OR = 2.66; 95% CI: 1.30–5.42) and number of cigarettes smoked per day (CPD) with heaviness of nicotine addiction measured by the Fagerström Test for Nicotine Dependence (FTND) (OR = 2.60; 95% CI: 1.24–5.43). No association between these polymorphisms and other phenotypes was found. Similarly, the association between rs588765, rs6495308, rs578776, and analyzed phenotypes was not confirmed. This study provides strong evidence for the role of the CHRNA5-CHRNA3-CHRNB4 cluster in heaviness of nicotine addiction.

Genetic variation in personality traits explains genetic overlap between borderline personality features and substance use disorders

AIMS

To examine the genetic overlap between borderline personality features (BPF) and substance use disorders (SUDs) and the extent to which variation in personality traits contributes to this covariance.

DESIGN

Genetic structural equation modelling was used to partition the variance in and covariance between personality traits, BPF and SUDs into additive genetic, shared and individual-specific environmental factors.

SETTING

All participants were registered with the Australian Twin Registry.

PARTICIPANTS

A total of 3127 Australian adult twins participated in the study.

MEASUREMENTS

Diagnoses of DSM-IV alcohol and cannabis abuse/dependence (AAD; CAD) and nicotine dependence (ND) were derived via computer-assisted telephone interview. BPF and five-factor model personality traits were derived via self-report questionnaires.

FINDINGS

Personality traits, BPF and substance use disorders were partially influenced by genetic factors with heritability estimates ranging from 0.38 (neuroticism; 95% confidence interval: 0.30-0.45) to 0.78 (CAD; 95% confidence interval: 0.67-0.86). Genetic and individual-specific environmental correlations between BPF and SUDs ranged from 0.33 to 0.56 (95% CI = 0.19-0.74) and 0.19-0.32 (95% CI = 0.06-0.43), respectively. Overall, there was substantial support for genetic influences that were specific to AAD, ND and CAD (30.76-68.60%). Finally, genetic variation in personality traits was responsible for 11.46% (extraversion for CAD) to 59.30% (neuroticism for AAD) of the correlation between BPF and SUDs.

CONCLUSIONS

Both genetic and individual-specific environmental factors contribute to comorbidity between borderline personality features and substance use disorders. A substantial proportion of this comorbidity can be attributed to variation in normal personality traits, particularly neuroticism.

Relationship between leukocyte telomere length and personality traits in healthy subjects

BACKGROUND

It has been shown that certain personality traits are related to mortality and disease morbidity, but the biological mechanism linking them remains unclear. Telomeres are tandem repeat DNA sequences located at the ends of chromosomes, and shorter telomere length is a predictor of mortality and late-life disease morbidity. Thus, it is possible that personality traits influence telomere length. In the present study, we examined the relationship of leukocyte telomere length with personality traits in healthy subjects.

SUBJECTS AND METHODS

The subjects were 209 unrelated healthy Japanese who were recruited from medical students at 4th-5th grade. Assessment of personality traits was performed by the Revised NEO Personality Inventory (NEO-PI-R) and the Temperament and Character Inventory (TCI). Leukocyte relative telomere length was determined by a quantitative real-time PCR method for a ratio of telomere/single copy gene.

RESULTS

In the stepwise multiple regression analysis, shorter telomere length was related to lower scores of neuroticism (P<0.01) and conscientiousness (P<0.05) of the NEO-PI-R, and lower scores of harm avoidance (P<0.05) and reward dependence (P<0.05) of the TCI.

CONCLUSIONS

The present study suggests that leukocyte telomere length is associated with some personality traits, and this association may be implicated in the relationship between personality traits and mortality.

A twin study of alcohol dependence, binge eating, and compensatory behaviors

OBJECTIVE

Rates of alcohol dependence are elevated in women with eating disorders who engage in binge eating or compensatory behaviors compared with women with eating disorders who do not report binge eating or compensatory behaviors and with healthy controls. Alcohol dependence, binge eating, and compensatory behaviors are heritable; however, it is unclear whether a shared genetic liability contributes to the phenotypic association among these traits, and little information exists regarding this shared liability in men. We investigated genetic and environmental correlations among alcohol dependence, binge eating, and compensatory behaviors in male and female twins.

METHOD

Participants included 5,993 same- and opposite-sex twins from the Australian Twin Registry who completed a modified version of the Semi-Structured Assessment for the Genetics of Alcoholism that assessed lifetime alcohol dependence and binge eating as defined in the Diagnostic and Statistical Manual of Mental Disorders, Third Edition, Revised. Compensatory behaviors were assessed via a general health questionnaire in women only. Biometrical twin models estimated genetic and environmental influences on alcohol dependence, binge eating, and compensatory behaviors.

RESULTS

In women, the multivariate twin model suggested that additive genetic and nonshared environmental effects influenced alcohol dependence, binge eating, and compensatory behaviors, with heritability estimates ranging from 38% to 53%. The best-fitting sex-limitation model was a common effects model that equated all genetic and nonshared environmental influences in men and women. The heritability estimates were 50% and 38% for alcohol dependence and binge eating, respectively. Overall, there were significant genetic correlations between alcohol dependence and binge eating, alcohol dependence and compensatory behaviors, and binge eating and compensatory behaviors.

CONCLUSIONS

These findings indicate that common genetic factors may underlie the vulnerability to alcohol dependence and the liability to binge eating and compensatory behaviors.

Exploring alternate processes contributing to the association between maternal smoking and the smoking behavior among young adult offspring

INTRODUCTION

Maternal smoking during pregnancy (MSP) is a known risk factor for regular smoking in young adulthood and may pose a risk independently of mother's lifetime smoking. The processes through which MSP exerts this influence are unknown but may occur through greater smoking quantity and frequency following initiation early in adolescence or increased sensitivity to nicotine dependence (ND) at low levels of smoking.

METHODS

This study used path analysis to investigate adolescent smoking quantity, smoking frequency, and ND as potential simultaneous mediating pathways through which MSP and mother's lifetime smoking (whether she has ever smoked) increase the risk of smoking in young adulthood among experimenters (at baseline, <100 cigarettes/lifetime) and current smokers (>100 cigarettes/lifetime).

RESULTS

For experimenters, MSP was directly associated with more frequent young adult smoking and was not mediated by adolescent smoking behavior or ND. Independently of MSP, the effect of mother's lifetime smoking was fully mediated through frequent smoking and was heightened ND during adolescence. Controlling for MSP eliminated a previously observed direct association between mother's lifetime smoking and future smoking among experimenters. For current smokers, only prior smoking behavior was associated with future smoking frequency.

CONCLUSIONS

These results seem to rule out sensitivity to ND and increased smoking behavior as contributing pathways of MSP. Further, the impact of MSP on young adult smoking extends beyond that of having an ever-smoking mother. Future work should test other possible mediators; for example, MSP-related epigenetic changes or gene variants influencing the brain's nicotine response.

Smoking-specific parenting and smoking onset in adolescence: the role of genes from the dopaminergic system (DRD2, DRD4, DAT1 genotypes)

Although only few studies have shown direct links between dopaminergic system genes and smoking onset, this does not rule out the effect of a gene-environment interaction on smoking onset. Therefore, the aim of this study was to examine the associations between smoking-specific parenting (i.e., frequency and quality of communication and house rules) and smoking onset while considering the potential moderating role of dopaminergic system genes (i.e., DRD2, DRD4, and DAT1 genotypes). Data from five annual waves of the 'Family and Health' project were used. At time 1, the sample comprised 365 non-smoking adolescents (200 younger adolescents, mean age = 13.31, SD = .48; 165 older adolescents, mean age = 15.19, SD = .57). Advanced longitudinal analyses were used (i.e., logistic regression analyses, (dual) latent growth curves, and cross-lagged path models). The results showed a direct effect of quality of communication on smoking onset. No direct effects were found for frequency of communication and house rules. Furthermore, no direct and moderating effects of the DRD2, DRD4, or DAT1 genotypes were found. In conclusion, the findings indicated that the effects of smoking-specific parenting on smoking are similar for adolescent carriers and non-carriers of the dopaminergic system genes.

Effects of nicotine on emotional distraction of attentional orienting: evidence of possible moderation by dopamine type 2 receptor genotype

INTRODUCTION

Growing evidence suggests that attentional bias to, and distraction by, emotional stimuli may moderate affective states and motivation for nicotine and other drug use.

METHODS

The present study assessed the effects of nicotine and dopamine receptor genotype on distraction by emotional pictures, during a modified spatial attention task, in 46 overnight-deprived smokers.

RESULTS

Relative to placebo, 14mg nicotine patch produced shorter overall reaction times (RTs) and individuals with two dopamine type 2 receptor (DRD2) A2 alleles exhibited the greatest RT benefit from nicotine following emotionally negative pictures after the longest cue-target delay (800ms), but benefitted least from nicotine following positive pictures after the shortest delay (400ms). In contrast, at the shortest delay, A1 carriers did not benefit from nicotine following emotionally negative pictures but did following positive ones.

CONCLUSIONS

These genetic differences in the effects of nicotine on attention immediately following emotionally positive versus negative stimuli may reflect differential excitatory and inhibitory transmitter processes related to approach (reward) and avoidance (punishment) sensitivities of dopamine-related neural networks that support positive and negative affect.

Life stress, the dopamine receptor gene, and emerging adult drug use trajectories: a longitudinal, multilevel, mediated moderation analysis

This study was designed to examine the prospective relations of life stress and genetic status with increases in drug use. African Americans (N = 399) in rural Georgia (Wave 1 mean age = 17 years) provided three waves of data across 27.5 months and a saliva sample from which the dopamine receptor D4 (DRD4) gene was genotyped. Multilevel growth curve modeling analysis indicated that emerging adults manifested the highest escalations in drug use when they reported high life stress and carried an allele of DRD4 with 7 or more repeats (7 + R allele). In addition, emerging adults who reported high life stress and carried the 7 + R allele evinced the largest increases in two proximal risk factors for drug use: affiliations with drug-using companions and drug use vulnerability cognitions. Furthermore, when the Gene × Environment interaction effects on the increases in affiliations with drug-using companions and vulnerability cognitions were entered into the model forecasting drug use, the Life Stress × DRD4 Status interaction on drug use became nonsignificant in the presence of the risk mechanisms. This finding provides an example of "second generation" Gene × Environment interaction research in which the interaction's effects on proximal risk mechanisms account for its effects on outcomes.

Risk factors for adolescent smoking: parental smoking and the mediating role of nicotine dependence

BACKGROUND

Parental smoking and early-emerging nicotine dependence symptoms are well-documented risk factors for adolescent smoking. However, very little is known about the mediating pathways through which these risk factors may act, or whether parental smoking may cause or signal early-emerging nicotine dependence symptoms.

METHODS

Data were drawn from the longitudinal Social and Emotional Contexts of Adolescent Smoking Patterns Study. Adolescents who had smoked under 100 cigarettes in their lifetime (n=594; low-exposure group) and adolescents who had smoked over 100 cigarettes, but fewer than 5 cigarettes per day (n=152) were included in the analyses. Path analysis was performed on longitudinal data to investigate the association between parental smoking and smoking frequency at the 48 months follow-up, both directly and through mediating variables of smoking frequency, smoking quantity, and nicotine dependence.

RESULTS

Father's smoking was associated with higher adolescent nicotine dependence scores at the baseline assessment wave. Structural equation modeling revealed that mother's smoking at baseline was associated with adolescent's smoking frequency at the 48-month follow-up, and its effect was partially mediated by both smoking frequency and nicotine dependence among low-exposure adolescent smokers.

CONCLUSIONS

Parental smoking is a risk factor for future smoking in low-exposure adolescent smokers, above and beyond the risks posed by smoking behavior and nicotine dependence. Moreover, parental smoking is associated with early-onset nicotine dependence in low-exposure adolescent smokers. As an easily measureable risk factor, parent smoking status can be used to identify and intervene with novice adolescent smokers who are at high risk for chronic smoking behavior.

Association of the 5-HTT gene-linked promoter region (5-HTTLPR) polymorphism with psychiatric disorders: review of psychopathology and pharmacotherapy

Serotonin (5-HT) regulates important biological and psychological processes including mood, and may be associated with the development of several psychiatric disorders. An association between psychopathology and genes that regulate 5-HT neurotransmission is a robust area of research. Identification of the genes responsible for the predisposition, development, and pharmacological response of various psychiatric disorders is crucial to the advancement of our understanding of their underlying neurobiology. This review highlights research investigating 5-HT transporter (5-HTTLPR) polymorphism, because studies investigating the impact of the 5-HTTLPR polymorphism have demonstrated significant associations with many psychiatric disorders. Decreased transcriptional activity of the S allele ("risk allele") may be associated with a heightened amygdala response leading to anxiety-related personality traits, major depressive disorder, suicide attempts, and bipolar disorder. By contrast, increased transcriptional activity of the L allele is considered protective for depression but is also associated with completed suicide, nicotine dependence, and attention deficit hyperactivity disorder. For some disorders, such as post-traumatic stress disorder and major depressive disorder, the research suggests that treatment response may vary by allele (such as an enhanced response to serotonin specific reuptake inhibitors in patients with major depressive disorder and post-traumatic stress disorder with L alleles), and for alcohol dependence, the association and treatment for S or L alleles may vary with alcoholic subtype. While some studies suggest that 5-HTTLPR polymorphism can moderate the response to pharmacotherapy, the association between 5-HTTLPR alleles and therapeutic outcomes is inconsistent. The discovery of triallelic 5-HTTLPR alleles (L(A)/L(G)/S) may help to explain some of the conflicting results of many past association studies, while concurrently providing more meaningful data in the future. Studies assessing 5-HTTLPR as the solitary genetic factor contributing to the etiology of psychiatric disorders continue to face the challenges of statistically small effect sizes and limited replication.

Cigarette experimentation in Mexican origin youth: psychosocial and genetic determinants

BACKGROUND

Established psychosocial risk factors increase the risk for experimentation among Mexican origin youth. Now, we comprehensively investigate the added contribution of select polymorphisms in candidate genetic pathways associated with sensation seeking, risk taking, and smoking phenotypes to predict experimentation.

METHODS

Participants (N = 1,118 Mexican origin youth) recruited from a large population-based cohort study in Houston, TX, provided prospective data on cigarette experimentation over 3 years. Psychosocial data were elicited twice-baseline and final follow-up. Participants were genotyped for 672 functional and tagging variants in the dopamine, serotonin, and opioid pathways.

RESULTS

After adjusting for gender and age, with a Bayesian False Discovery Probability set at 0.8 and prior probability of 0.05, six gene variants were significantly associated with risk of experimentation. After controlling for established risk factors, multivariable analyses revealed that participants with six or more risk alleles were 2.25 [95% confidence interval (CI), 1.62-3.13] times more likely to have experimented since baseline than participants with five or fewer. Among committed never-smokers (N = 872), three genes (OPRM1, SNAP25, HTR1B) were associated with experimentation as were all psychosocial factors. Among susceptible youth (N = 246), older age at baseline, living with a smoker, and three different genes (HTR2A, DRD2, SLC6A3) predicted experimentation.

CONCLUSIONS

Our findings, which have implications for development of culturally specific interventions, need to be validated in other ethnic groups.

IMPACT

These results suggest that variations in select genes interact with a cognitive predisposition toward smoking. In susceptible adolescents, the impact of the genetic variants appears to be larger than committed never-smokers.

Smoking and Cloninger's Temperament and Character Inventory

INTRODUCTION

Cloninger's neuropsychopharmacological theory identifies four temperament traits and three character traits that are largely heritable and are associated with addictions.

METHODS

We tested whether these personality traits were associated with smoking behavior and predicted smoking cessation and tobacco withdrawal symptoms. We conducted an Internet cohort study in 2005-2009. The Temperament and Character Inventory (TCI, 226 items, French version) was assessed in 2,993 people (1,593 current, 969 former, and 419 never-smokers). Subsets of participants indicated their smoking status after 30 days (n = 1,452, 48.5%) and answered the TCI again and reported tobacco withdrawal symptoms after 61 days (n = 644, 21.5%).

RESULTS

Compared with never- and former smokers, daily smokers had higher scores of Harm Avoidance (HA) and lower scores of Persistence and Self-Directedness (SD). Daily smokers had higher scores of Novelty Seeking than never-smokers. In daily smokers, the level of tobacco dependence was associated with higher scores of HA and lower scores of SD. In the 60 daily smokers who had stopped smoking after 61 days, after adjustment for tobacco dependence level and baseline tobacco withdrawal ratings, SD predicted lower scores of depressed mood and anxiety at 61-day follow-up and HA predicted higher scores of depressed mood at 61-day follow-up. Personality ratings did not predict smoking cessation at follow-up in daily smokers or relapse in former smokers.

DISCUSSION

A consistent association was found between smoking and high HA and low SD. Knowledge about these associations may be useful to clinicians to tailor counseling.

Challenging the "inoffensiveness" of regular cannabis use by its associations with other current risky substance use--a census of 20-year-old Swiss men

3,537 men enrolling in 2007 for mandatory army recruitment procedures were assessed for the co-occurrence of risky licit substance use among risky cannabis users. Risky cannabis use was defined as at least twice weekly; risky alcohol use as 6+ drinks more than once/monthly, or more than 20 drinks per week; and risky tobacco use as daily smoking. Ninety-five percent of all risky cannabis users reported other risky use. They began using cannabis earlier than did non-risky users, but age of onset was unrelated to other risky substance use. A pressing public health issue among cannabis users stems from risky licit substance use warranting preventive efforts within this age group.

Neurotransmission-related genetic polymorphisms, negative affectivity traits, and gender predict tobacco abstinence symptoms across 44 days with and without nicotine patch

Genetic and personality trait moderators of tobacco abstinence-symptom trajectories were assessed in a highly controlled study. Based on evidence suggesting their importance in stress reactivity and smoking, moderators studied were serotonin transporter gene (5-HTTLPR) and dopamine D2 receptor gene (DRD2) polymorphisms and personality traits related to negative affect (NA). Smokers were randomly assigned to quit smoking with nicotine or placebo patches. Financial incentives resulted in 80% verified abstinence across the 44-day study. Individuals with 1 or 2 short alleles of 5-HTTLPR (S carriers) experienced larger increases in NA symptoms than did those without a short allele. Nicotine replacement therapy (NRT) alleviated anxiety only in S carriers. NRT reduced NA to a greater extent in DRD2 A1 carriers than in A2A2 individuals during the 1st 2 weeks of treatment (when on the 21-mg patch); however, A1 carriers experienced a renewal of NA symptoms when switched to the 7-mg patch and when off the patch, while A2A2 individuals continued to benefit from NRT. The results suggest that the effects of genotype and treatment may vary across different durations of abstinence, treatment doses, and genotypes.

Substance use, trait measures, and subjective response to nicotine in never-smokers stratified on parental smoking history and sex

INTRODUCTION

Male and female never-smokers stratified on parental history of smoking were tested for possible differences in susceptibility to the hedonic effects of nicotine.

METHODS

We recruited nicotine-exposed never-smokers with two never-smoking biological parents (PH-) or two ever-smoking biological parents (PH+). After completing a baseline assessment battery focusing on conditions or behaviors associated with smoking, participants were tested for subjective and hedonic effects in response to administration of three different nicotine doses (0.0, 0.5, and 1.0 mg) via nasal spray. Physiological and biochemical reactivity also was monitored.

RESULTS

PH+ were significantly more likely to report having experienced a "buzz" upon early smoking experimentation and to have histories of alcohol abuse and alcoholism; they also scored higher on disordered eating. In response to nicotine dosing, PH+ reported an increase in depressed mood, compared with a minimal response in PH-, in keeping with our expectation that nicotine would have more pronounced effects in PH+. Regardless of parental history, women reported experiencing greater anxiety in response to the highest nicotine dose, compared with men.

DISCUSSION

Further exploration in larger samples, using more stringent selection criteria, a wider range of measures, and a less aversive dosing method, may provide a full test of the possible utility of the parental history model for illuminating biobehavioral mechanisms underlying response to nicotine. Also important would be broadening the scope of inquiry to include comparisons with ever-smokers to determine what protected PH+ from becoming smokers, despite the presence of factors that might be expected to decrease resilience and increase susceptibility.

Gene-gene interactions among CHRNA4, CHRNB2, BDNF, and NTRK2 in nicotine dependence

BACKGROUND

Epidemiological data indicate that nicotine dependence (ND) are influenced by genes, environmental factors, and their interactions. Although it has been documented from molecular experiments that brain-derived neurotrophic factor (BDNF) exerts its functions via neurotrophic tyrosine kinase receptor 2 (NTRK2) and both alpha 4 (CHRNA4) and beta 2 (CHRNB2) subunits are required to form functional alpha 4 beta 2-containing nicotinic receptors (nAChRs), no study is reported demonstrating that there exist gene-gene interactions among the four genes in affecting ND.

METHODS

To determine if gene-gene interactions exist among the four genes, we genotyped six single nucleotide polymorphisms (SNPs) for CHRNA4 and BDNF, nine SNPs for NTRK2, and four SNPs for CHRNB2 in a case-control sample containing 275 unrelated smokers with a Fagerström Test for Nicotine Dependence score of 4.0 or more and 348 unrelated nonsmokers.

RESULTS

By using a generalized multifactor dimensionality reduction algorithm recently developed by us, we found highly significant gene-gene interactions for the gene pairs of CHRNA4 and CHRNB2, CHRNA4 and NTRK2, CHRNB2 and NTRK2, and BDNF and NTRK2 (p < .01 for all four gene pairs) and significant gene-gene interaction between CHRNA4 and BDNF (p = .031) on ND. No significant interaction was detected for CHRNB2 and BDNF (p = .068).

CONCLUSIONS

Our study provides first evidence on the presence of gene-gene interaction among the four genes in affecting ND. Although CHRNB2 alone was not significantly associated with ND in several previously reported association studies on ND, we found it affects ND through interactions with CHRNA4 and NTRK2.

Cannabinoid receptor 1 gene association with nicotine dependence

CONTEXT

The endogenous cannabinoid system has been implicated in drug addiction in animal models. The cannabinoid receptor 1 (CNR1) gene is 1 of the 2 receptors expressed in the brain. It has been reported to be associated with alcoholism and multiple drug abuse and dependence.

OBJECTIVE

To test the hypothesis that the CNR1 gene is associated with nicotine dependence.

DESIGN

Genotype-phenotype association study. Ten single-nucleotide polymorphisms were genotyped in the CNR1 gene in 2 independent samples. For the first sample (n = 688), a 3-group case-control design was used to test allele association with smoking initiation and nicotine dependence. For the second sample (n = 961), association was assessed with scores from the Fagerström Test for Nicotine Dependence (FTND). Settings Population samples selected from the Mid-Atlantic Twin Registry.

PARTICIPANTS

White patients aged 18 to 65 years who met the criteria of inclusion.

MAIN OUTCOME MEASURES

Fagerström Tolerance Questionnaire and FTND scores.

RESULTS

Significant single-marker and haplotype associations were found in both samples, and the associations were female specific. Haplotype 1-1-2 of markers rs2023239-rs12720071-rs806368 was associated with nicotine dependence and FTND score in the 2 samples (P < .001 and P = .009, respectively).

CONCLUSION

Variants and haplotypes in the CNR1 gene may alter the risk for nicotine dependence, and the associations are likely sex specific.

Lack of association between serotonin transporter gene polymorphism 5-HTTLPR and smoking among Polish population: a case-control study

BACKGROUND

A better understanding of the genetic determinants of tobacco smoking might help in developing more effective cessation therapies, tailored to smokers' genotype. Insertion/deletion polymorphism in the promoter region of the serotonin transporter gene (5-HTTLPR) has been linked to vulnerability to smoking and ability to quit. We aimed to determine whether 5-HTTLPR genotype is associated with smoking behavior in Caucasians from Northern Poland and to investigate other risk factors for tobacco smoking.

METHODS

5-HTTLPR genotypes were determined in 149 ever smokers (66 females; mean age 53.0 years) and 158 gender and ethnicity matched never smoking controls (79 females; mean age 45.0 years) to evaluate the association of this polymorphism with ever smoking status. Analysis of smokers was performed to evaluate the role of 5-HTTLPR in the age of starting regular smoking, the number of cigarettes smoked daily, pack-years, FTND score, duration of smoking, and the mean length of the longest abstinence on quitting. Genotype was classified according to the presence or absence of the short (S) allele vs. the long (L) allele of 5-HTTLPR (i.e., S/S + S/L vs. L/L). Logistic regression analysis was also used to evaluate correlation between ever smoking and several selected variables.

RESULTS

We found no significant differences in the rates of S allele carriers in ever smokers and never smokers, and no relationship was observed between any quantitative measures of smoking and the polymorphism. Multivariate analysis demonstrated significant association between the older age (OR = 4.03; 95% CI: 2.33-6.99) and alcohol dependence (OR = 10.23; 95% CI: 2.09-50.18) and smoking.

CONCLUSION

5-HTTLPR seems to be not a major factor determining cigarette smoking in Poles. Probably, the risk of smoking results from a large number of genes, each contributing a small part of the overall risk, while numerous non-genetic factors might strongly influence these genetic undergrounds of susceptibility to smoking.

Genes and cigarette smoking

AIMS

Attempts to further our understanding of the determinants of cigarette smoking, tobacco addiction and related behaviours have included the dissection of genetic influences on these phenotypes. This review summarizes the current state of evidence from both twin and adoption studies and molecular genetic studies. We also review future research horizons and the direction which studies of this kind are likely to take in the near future.

FINDINGS

There is consistent evidence from twin and adoption studies that genetic factors play a role in the aetiology of cigarette smoking. Nevertheless, despite a large number of candidate gene studies, and a smaller number of linkage studies, few reported associations and chromosomal regions of interest have proved to replicate reliably. This is due most probably to the small effects of individual loci on complex behaviours such as smoking.

CONCLUSIONS

Future research is likely to include the study of gene x environment interactions (including gene x treatment interactions, which offer the prospect of genetically tailored smoking cessation treatment) and the use of more sophisticated smoking-related phenotypes, such as longitudinal smoking trajectories, and intermediate phenotypes which use technologies such as neuroimaging and other laboratory and biobehavioural measures.

Genome-wide linkage scan for nicotine dependence in European Americans and its converging results with African Americans in the Mid-South Tobacco Family sample

Previously, we reported a genome-wide scan for nicotine dependence (ND) in the African American (AA) sample of the Mid-South Tobacco Family (MSTF) cohort. In this study, we conducted a genome-wide scan in 629 individuals representing 200 nuclear families of European American (EA) origin of the MSTF cohort with the goals of identifying vulnerability loci for ND in the EAs and determining converging regions across the ethnic groups. We examined 385 autosomal microsatellite markers for ND, which was assessed by smoking quantity (SQ), the Heaviness of Smoking Index (HSI) and the Fagerström test for ND (FTND). After performing linkage analyses using various methods implemented in the GENEHUNTER and SAGE programs, we found eight regions on chromosomes 2, 4, 9-12, 17 and 18 that met the criteria for suggestive linkage to at least one ND measure in the EA sample. Of these, the region on chromosome 4 at 43 cM showed suggestive linkage to indexed SQ, the HSI and the FTND, and the region on chromosome 9 at 24 cM showed suggestive linkage to the HSI and the FTND. To increase detection power, we analyzed a combined AA and EA sample using age, gender and ethnicity as covariates and found that the region on chromosome 12 near marker D12S372 showed significant linkage to SQ. Additionally, we found six regions on chromosomes 9-11, 13 and 18 that showed suggestive linkage to at least one ND measure in the combined sample. When we compared the linkage peaks detected for ND among the two samples and a combined sample, we found that four regions on chromosomes 9 (two regions), 11 and 18 overlapped. On the other hand, we identified five regions on chromosomes 2, 4, 10, 12 and 17 that showed linkage to ND only in the EA sample, and two regions on chromosomes 10 and 13 that showed linkage to ND only in the AA sample. For those linkages identified in only one sample, we found that the combined analysis of AA plus EA samples actually decreased the linkage signal. This indicates that some chromosomal regions may be more homogenous than others across the ethnic samples. All regions except for the one on chromosome 12 have been detected at nominally significant levels in other studies, providing independent replication of ND loci in different populations.

Do the same genetic and environmental effects underlie the covariation of alcohol dependence, smoking, and aggressive behaviour?

We investigated genetic and environmental effects on alcohol dependence, smoking, and aggressive behaviour, as well as sex differences in these effects and whether these effects were the same for the three phenotypes. There were 3141 male (mean age 26.2 [S.E.=0.1]) and 6026 female (mean age 26.1 [S.E.=0.1]) participants in this extended twin study. Alcohol Use Disorder Identification Test (AUDIT), number of cigarettes smoked, and two subscales of Aggression Questionnaire (AQ) were used to assess the phenotypes. All three were positively interrelated with males exhibiting higher levels on each phenotype. Multivariate model fitting identified genetic effects on all phenotypes for both men and women ranging between 69% (aggressive behaviour in women) and 78% (alcohol dependence in men). The effects were stronger in men for alcohol dependence and smoking. There were no qualitative genetic sex differences. Genetic correlations between all phenotypes were substantial.

Association of the serotonin transporter gene, neuroticism and smoking behaviours

Cigarette consumption and smoking cessation are influenced in part by genes. Personality traits have also been implicated in the aetiology of smoking. Neuroticism, a personality trait with a heritable component, correlates well with anxiety and depression, increasing the risk of being a smoker and decreasing the chance of smoking cessation. Several prior studies in non-British populations have given conflicting results as to whether some genetic polymorphisms affect the relationship between smoking and neuroticism. This study investigated the influence of serotonin transporter (5HTTLPR) genotypes on a composite measure of neuroticism and cigarette consumption/smoking cessation in a British population. Although neuroticism was significantly associated with cigarette consumption and smoking cessation, genotype did not affect this relationship. Our results do not support initial interest in utilising 5HTTLPR genotypes in combination with neuroticism ratings for predicting outcome in smoking cessation clinical settings.

Associations between Cloninger's temperament dimensions and acute tobacco withdrawal

This study examined associations between three temperament dimensions measured by the Temperament and Character Inventory-125 [Cloninger, C.R. (1992). The Temperament and Character Inventory-125 (TCI-125; Version 1.)] and tobacco abstinence effects. Smokers (N=203, >/= 15 cigarettes/day) attended two laboratory sessions, one following 12 h of abstinence and the other following ad libitum smoking (order counterbalanced). Participants completed measures of withdrawal symptoms, cigarette urges, and affect. Smokers high in Novelty Seeking reported greater abstinence-induced increases in several nicotine withdrawal symptoms, negative affect, and cigarette craving. Smokers high in Harm Avoidance reported greater abstinence-induced increases in negative affect and urges to smoke to relieve distress. Reward Dependence was not associated with abstinence effects. Novelty Seeking and Harm Avoidance showed independent predictive associations with negative affect and urges, and their associations with abstinence effects persisted when controlling for FTND scores. Smokers with different temperaments display different patterns of acute tobacco withdrawal, and may benefit from treatments matched to their particular abstinence profile.

Lack of Association of Alcohol Dependence and Habitual Smoking With Catechol-O-methyltransferase

OBJECTIVE

To test whether variation in the gene encoding the enzyme catechol-O-methyltransferase (COMT), which catalyzes the breakdown of dopamine and other catecholamine neurotransmitters, is associated with the risk for alcohol dependence and habitual smoking.

METHODS

Single nucleotide polymophisms (SNPs) were genotyped in a sample of 219 multiplex alcohol-dependent families of European American descent from the Collaborative Study on the Genetics of Alcoholism (COGA). Family-based tests of association were performed to evaluate the evidence of association between the 18 SNPs distributed throughout COMT, including the functional Val158Met polymorphism, and the phenotypes of alcohol dependence, early onset alcohol dependence, habitual smoking, and comorbid alcohol dependence and habitual smoking.

RESULTS

No significant, consistent evidence of association was found with alcohol dependence, early onset alcohol dependence, habitual smoking or the comorbid phenotype. There was no evidence that the functional Val158Met polymorphism, previously reported to be associated with these phenotypes, was associated with any of them.

CONCLUSION

Despite the substantial size of this study, we did not find evidence to support an association between alcohol dependence or habitual smoking and variation in COMT.

Exploring the inter-relationship of smoking age-at-onset, cigarette consumption and smoking persistence: genes or environment?

BACKGROUND

We investigated the genetic and environmental contributions to covariation between smoking age-at-onset, cigarette consumption and smoking persistence.

METHOD

Multivariate biometrical modelling methods were applied to questionnaire data from Australian twins and their siblings (14 472 individuals from 6247 families). The contributions of genetic and environmental factors to covariation between the three traits were estimated, allowing for sex differences in both trait prevalence and the magnitude of genetic and environmental effects.

RESULTS

All traits were moderately heritable in males and females (estimates between 0.40 and 0.62), but there were sex differences in the extent to which additive genetic influences were shared across traits. Twin-specific environmental factors accounted for a substantial proportion of the variance in smoking age-at-onset in females (0.19) and males (0.12), but had little influence (<0.08) on other traits. Unique environmental factors were estimated to have a moderate influence on smoking age-at-onset (0.17 for females, 0.19 for males), but a stronger influence on other traits (between 0.39 and 0.49).

CONCLUSIONS

These results provide some insight into observed sex differences in smoking behaviour, and suggest that searching for pleiotropic genes may prove fruitful. However, further work on phenotypic definitions of smoking behaviour, particularly persistence, is warranted.

Cohort trends in prevalence and spousal concordance for smoking

Evaluation of the pattern of smoking prevalence over time could provide insight for disease prevention and tobacco control policy. Examination of assortative mating is important in assessing the relative contribution of genetic and environmental influences in behavior genetics. A significant spousal concordance for smoking could imply assortative mating behavior and have potential influence on the risk for offspring smoking. Using intergenerational data from large scale adult twin panels in Australia, the present study examined the patterns of prevalence and spousal concordance of lifetime smoking across a wide range of birth cohorts. Data were collected for more than 16,000 twins, their spouses, parents, and parents-reported grandparents. The measurement models were used to calculate prevalence and spousal concordance for smoking. Prevalence of lifetime smoking for females increased significantly over successive cohorts, and was higher for twins (0.28-0.49) than for their parents or grandparents (0.06-0.42). Smoking prevalence was still higher in males than in females for the twins (0.49-0.69), and parental or grandparental (0.62-0.77) generations, but the gender differences largely decreased in younger cohorts. Moderate but significant spousal correlations were found across cohorts and generations, which were higher for twins (0.39-0.55) than for their parents and grandparents (0.19-0.49). Despite using a simplified smoking assessment, findings in this study demonstrated changes of lifetime smoking patterns across birth cohorts and the presence of assortative mating for smoking behavior.

Ideal self-image congruency as a motivator for smoking: the moderating effects of personality traits

A content analysis showed that cigarette advertising in Taiwan from June 2001 to May 2003 portrayed smokers as masculine, adventurous, pleasure-loving, and sociable. A survey of 1,490 high school students further indicated that smokers and nonsmokers differ in the congruency between their ideal self-images and the perceived smoker image on these 4 image dimensions. The self-smoker image congruency was greater for smokers than for nonsmokers and was positively associated with attitudes toward cigarette advertising Most important, this study demonstrated that participants' personality traits moderated self-smoker image congruency effects on smoking attitudes. Implications and suggestions for antismoking campaigns are discussed.

Genetic and environmental influences on extreme personality dispositions in adolescent female twins

BACKGROUND

The objective was to determine whether the pattern of environmental and genetic influences on deviant personality scores differs from that observed for the normative range of personality, comparing results in adolescent and adult female twins.

METHODS

A sample of 2,796 female adolescent twins ascertained from birth records provided Junior Eysenck Personality Questionnaire data. The average age of the sample was 17.0 years (S.D. 2.3). Genetic analyses of continuous and extreme personality scores were conducted. Results were compared for 3,178 adult female twins.

RESULTS

Genetic analysis of continuous traits in adolescent female twins were similar to findings in adult female twins, with genetic influences accounting for between 37% and 44% of the variance in Extraversion (Ex), Neuroticism (N), and Social Non-Conformity (SNC), with significant evidence of shared environmental influences (19%) found only for SNC in the adult female twins. Analyses of extreme personality characteristics, defined categorically, in the adolescent data and replicated in the adult female data, yielded estimates for high N and high SNC that deviated substantially (p < .05) from those obtained in the continuous trait analyses, and provided suggestive evidence that shared family environment may play a more important role in determining personality deviance than has been previously found when personality is viewed continuously. However, multiple-threshold models that assumed the same genetic and environmental determinants of both normative range variation and extreme scores gave acceptable fits for each personality dimension.

CONCLUSIONS

The hypothesis of differences in genetic or environmental factors responsible for N and SNC among female twins with scores in the extreme versus normative ranges was partially supported, but not for Ex.

A genome-wide screen for nicotine dependence susceptibility loci

Genome-wide model free linkage analysis was conducted for nicotine dependence and tobacco use phenotypes in 607 members of 158 nuclear families consisting of at least two ever smokers (100 or more cigarettes smoked in lifetime). DNA from whole blood was genotyped for 739 autosomal microsatellite polymorphisms with an average inter-marker distance of 4.6 cM. A peak LOD score of 2.7 was observed on chromosome 6 for scores for the Fagerström Test for Nicotine Dependence. Exploratory analyses were conducted to determine whether sequence variation at other loci affected other measures of dependence or tobacco use. Four additional loci with LOD scores of 2.7 or more were associated with alternative measures of nicotine dependence, one with current frequency of use, and one with smoking cessation. Several of the corresponding support intervals were near putative loci reported previously (on chromosomes 6, 7, and 8) while others appear to be novel (on chromosomes 5, 16, and 19).

Assortative mating for cigarette smoking and for alcohol consumption in female Australian twins and their spouses

BACKGROUND

Non-random mating affects population variation for substance use and dependence. Developmentally, mate selection leading to positive spousal correlations for genetic similarity may result in increased risk for substance use and misuse in offspring. Mate selection varies by cohort and thus, assortative mating in one generation may produce marked changes in rates of substance use in the next. We aim to clarify the mechanisms contributing to spousal similarity for cigarette smoking and alcohol consumption.

METHODS

Using data from female twins and their male spouses, we fit univariate and bivariate twin models to examine the contribution of primary assortative mating and reciprocal marital interaction to spousal resemblance for regular cigarette smoking and nicotine dependence, and for regular alcohol use and alcohol dependence.

RESULTS

We found that assortative mating significantly influenced regular smoking, regular alcohol use, nicotine dependence and alcohol dependence. The bivariate models for cigarette smoking and alcohol consumption also highlighted the importance of primary assortative mating on all stages of cigarette smoking and alcohol consumption, with additional evidence for assortative mating across the two stages of alcohol consumption.

CONCLUSIONS

Women who regularly used, and subsequently were dependent on cigarettes or alcohol were more likely to marry men with similar behaviors. After mate selection had occurred, one partner's cigarette or alcohol involvement did not significantly modify the other partner's involvement with these psychoactive substances.

The serotonin transporter gene polymorphism is not associated with smoking behavior

Nicotine increases serotonin release in the brain and symptoms of nicotine withdrawal may be modulated by diminished serotonergic neurotransmission. The promoter region of the serotonin transporter gene, solute carrier family neurotransmitter transporter member 4 (SLC6A4), contains a functional tandem repeat polymorphism. The long (L) variant is more actively transcribed than the short (S) variant and is associated with a higher serotonin uptake. To investigate the potential role of this polymorphism for smoking behavior, SLC6A4 genotypes were determined in two different studies, the SMOKING GENES case-control study (470 current smokers and 419 subjects who had never smoked) and the cross-sectional Ludwigshafen risk and cardiovascular health (LURIC) study (777 current smokers and 1178 subjects who had never smoked). In the SMOKING GENES case-control study, SLC6A4 genotype frequencies were not statistically different between smokers (LL: 30.9%; LS: 46.8%; SS: 16.4%) and non-smokers (LL: 36.3%; LS: 41.8%; SS: 14.3%; P=0.13). Similar results were obtained in the cross-sectional LURIC study (smokers: LL, 36.5%, LS, 45.6%, SS, 17.9%; non-smokers: LL, 33.6%, LS, 48.9%, SS, 17.6%; P=0.33). SLC6A4 genotypes were furthermore not associated with Fagerstrom Tolerance Questionnaire score, packyears, number of cigarettes smoked per day or previous attempts to quit smoking. We conclude that the SLC6A4 promoter polymorphism is not a major determinant of smoking behavior in Caucasian.

Temperament characteristics, as assessed by the tridimensional personality questionnaire, moderate the response to sertraline in depressed opiate-dependent methadone patients

During a randomized, double-blind, placebo controlled study of the effects of sertraline in depressed methadone-maintained patients, 82 completed the tridimensional personality questionnaire (TPQ) to assess whether temperament dimensions can affect treatment-related changes in mood and drug use. Mood outcome significantly differed according to scores on the reward dependence scale (RD). Low RD participants displayed a significantly better mood response to sertraline than high RD participants. Participants with high harm avoidance (HA) scores were more likely to be abstinent at the end of the 12 week trial of sertraline than low HA participants. High persistence (P) participants were less likely to be abstinent at the end of the 12-week trial. These results suggest that temperament dimensions may be important for identifying substance dependent patients more likely to benefit from pharmacological interventions for comorbid depressive disorders.

The association between the DRD2 TaqI A polymorphism and smoking cessation in response to acupuncture in Koreans

OBJECTIVES

The response to acupuncture is presumed to differ with the individual; this variation might be due to genetic differences. Therefore, we examined whether the DRD2 TaqI A polymorphism is associated with the response to acupuncture in the treatment of smoking cessation in a Korean population.

SUBJECTS

A total of 231 healthy Korean male smokers participated in this study.

INTERVENTIONS

The subjects underwent three manual auricular acupuncture treatments in one week.

DESIGN AND OUTCOME MEASURES

After 1 week, high and low responders to the acupuncture treatment were selected according to their cigarette consumption and the desire to smoke. A DRD2 TaqI A restriction enzyme fragment length polymorphism (RFLP) study examined genomic DNA extracted from blood samples.

RESULTS

The proportions of high, intermediate, and low responders were 28.6, 55.4, and 16.0%, respectively. The RFLP study showed that the distribution of the DRD2*A genotype and allele frequencies differed significantly between the high and low responders (chi(2) test, p = 0.031 and 0.016, respectively), and that high responders had a higher DRD2*A2 allele frequency than low responders.

CONCLUSIONS

Our findings suggest that DRD2 TaqI A polymorphism is related to acupuncture response in smoking cessation treatment.

Dopamine receptor (DRD2) genotype‐dependent effects of nicotine on attention and distraction during rapid visual information processing

The effects of nicotine, distractor type, and dopamine type-2 receptor (DRD2) genotype on rapid visual information processing (RVIP) task performance were assessed in habitual smokers. Four RVIP tasks differed in terms of distractor location (central vs. peripheral) and distractor type (numeric vs. emotional). Each participant performed each of the tasks on two different days, once while wearing an active nicotine patch and once while wearing a placebo patch. Overall, the nicotine patch produced more accurate detection of and faster reaction times to target sequences; however, these effects varied with distractor type and genotype. Nicotine speeded reaction time more with left-visual-field (LVF) than right-visual-field (RVF) emotional distractors but speeded reaction time more with RVF than LVF numeric distractors, especially when the distractor digit matched the target sequence in terms of numeric oddness or evenness. Nicotine tended to facilitate performance more in individuals with at least one A1 allele than in homozygous A2A2 individuals, especially with numeric distractors presented to the left hemisphere. Nicotine tended to reduce distraction by negative stimuli more than other types of stimuli. Few gender differences were observed. The overall pattern of results was consistent with the view that nicotine modulates selective attention or subsequent information processing in a manner that depends partly on the emotional versus numeric nature of task distractors, DRD2 genotype, and the brain hemisphere that initially processes the distractors (visual field of distractor).

Association of the serotonin transporter promoter polymorphism with smoking behavior among adolescents

Serotonin transporter promoter polymorphism (5-HTTLPR) genotype was previously found associated with smoking behavior, difficulty in quitting smoking, and nicotine addiction; with non-replicated findings and contrasting results. Aim of the present study was to evaluate the possible association between 5-HTTLPR genotype and smoking behavior among adolescents, in relationship with psychological characteristics. Two hundred and ten Caucasian high school students (aged 14-19 years); 103 non-smokers, who have never smoked nicotine; and 107 tobacco smokers have been genotyped. Aggressiveness levels and temperamental traits were measured in both smokers and non-smokers, respectively, utilizing Buss-Durkee Hostility Inventory (BDHI) and Cloninger Three-Dimensional Personality Questionnaire (TPQ). Data about school performance have been also collected. The short-short (SS) genotype frequency was significantly higher among smokers compared with non-smokers (P = 0.023). The odds ratio for the SS genotype versus the long-long (LL) genotype frequency was 1.17 [95% CL (0.30-2.05)], when smokers were compared with non-smokers. The SS genotype frequency was significantly higher among heavy smokers with early onset, compared with moderate smokers with late onset (P = 0.042). BDHI irritability scores, NS scores at TPQ, and school failure frequency were significantly higher in smokers than in non-smokers. Multivariate model-fitting analysis evidenced a significantly greater relationship of genotype with irritability levels (BDHI scores) (0.34, P < 0.001) and temperament traits (NS scores) (0.36, P < 0.001), than with school performance (rate of school under-achievements) (0.18, P < 0.05) and nicotine smoking (number of cigarettes) (0.24, P < 0.01). Accordingly, factor-analysis showed that gene polymorphism contributes more directly to BDHI scores and NS scores (0.73; 0.71) than to smoking behavior and school under-achievement (0.54; 0.51). Our data suggest that a decreased expression of the gene encoding the 5-HTT transporter, due to "S" promoter polymorphism, may be associated with smoking behavior among adolescents and increased risk to develop nicotine dependence, possibly in relationship to personality traits, temperamental characteristics, and school under-achievements.

Pleiotropic effect of the TPH A779C polymorphism on nicotine dependence and personality

Recent studies from molecular genetics have suggested an association between the tryptophan hydroxylase 1 (TPH1) gene and nicotine addiction indicating a dysfunction of the serotonergic (5-HT) system in smoking behavior. In a sample of 252 healthy subjects, a significant association between variations observed in nicotine dependence and the heterozygous AC-genotype of the TPH A779C polymorphism could be demonstrated. Moreover, the heterozygous genotype was significantly associated with a personality trait of neurotic aggression (indirect hostility, negativism), as measured by the Buss-Durkee-Hostility-Inventory (BDHI). The positive heterosis effects with respect to nicotine addiction and personality support the idea that the TPH1 gene exerts pleiotropic effects.

Genetic susceptibility to substance dependence

Despite what is often believed, the majority of those who experiment with substances with a dependence potential do not develop dependence. However, there is a subpopulation of users that easily becomes dependent on substances, and these individuals exhibit pre-existing comorbid traits, including novelty seeking and antisocial behavior. There appears to be a genetic basis for the susceptibility to dependence and these comorbid traits. Animal studies have identified specific genes that can alter susceptibility to dependence and response to novelty. The mechanisms underlying the genetic susceptibility to dependence and response to novelty are complex, but genetic susceptibility plays a significant role in the transition from substance use to dependence and from chronic use to addiction. We discuss two models to explain how genetic variations alter dependence susceptibility. Identification of the specific genes involved in these processes would help to identify individuals that are vulnerable to dependence/addiction and to devise novel treatment strategies.

Depression vulnerability, cigarette smoking, and the serotonin transporter gene

People with current or past depression are more likely to have been smokers at some point in their lives. Smokers with depression histories are also less likely to quit. Attempts to understand this relationship are important insofar as they can help treatment efficacy for this group of smokers. Prior research indicates that different genetic variations affect the relationship between smoking and neuroticism. This study examined whether people with a short serotonin transporter genotype would likewise show a stronger relationship between depression vulnerability and smoking behavior than those with the long genotype. Although depression vulnerability was associated with smoking behaviors, genotype did not significantly affect this relationship. Discussion centered on possible reasons for varying results across conceptually similar studies.

The Genetics of Alcohol Intake and of Alcohol Dependence

BACKGROUND

Because alcohol has multiple dose-dependent consequences, it is important to understand the causes of individual variation in the amount of alcohol used. The aims of this study were to assess the long-term repeatability and genetic or environmental causes of variation in alcohol intake and to estimate the degree of overlap with causes of susceptibility to alcohol dependence.

METHODS

Data were used from three studies conducted between 1980 and 1995 on volunteer adult male and female Australian twin subjects. In each study, alcohol intake was reported both as quantity x frequency and as past-week data. Repeatability was calculated as correlations between occasions and between measures, and the effects of genes and environment were estimated by multivariate model fitting to the twin pair repeated measures of alcohol use. Relationships between mean alcohol use and the lifetime history of DSM-III-R alcohol dependence were tested by bivariate model fitting.

RESULTS

Repeatability of the alcohol intake measures was between 0.54 and 0.85, with the highest repeatability between measures within study and the lowest repeatability between the first and last studies. Reported alcohol consumption was mainly affected by genetic factors affecting all times of study and by nonshared environmental factors (including measurement error) unique to each time of study. Genes that affect alcohol intake do affect alcohol dependence, but genetic effects unique to dependence are also significant; environmental effects are largely unique to either intake and dependence.

CONCLUSIONS

Nearly all the repeatable component of variation in alcohol intake is due to genetic effects. Genes affecting intake also affect dependence risk, but there are other genes that affect dependence alone. Studies aiming to identify genes that affect alcohol use disorders need to test loci and candidate genes against both phenotypes.

MAO-B knockout mice exhibit deficient habituation of locomotor activity but normal nicotine intake

Low levels of monoamine oxidase-B (MAO-B) activity, such as those observed in smokers, are also associated with behavioral traits such as a heightened responsiveness to novelty. However, the exact mechanism by which low MAO-B activity influences smoking and heightened responsiveness to novelty is still poorly understood. We used MAO-B knockout (KO) mice to test the hypothesis that MAO-B concomitantly affects locomotor responses in a novel inescapable open field and nicotine intake. Male wild-type (WT) and MAO-B KO mice were placed in an inescapable open field and their horizontal locomotor activity was measured for 30 min per day for 5 days. MAO-B KO mice exhibited impaired within-session habituation of locomotor activity, as compared to WT mice. Separate groups of male WT and MAO-B KO mice were individually housed in their home cages with two water bottles. One of the bottles contained tap water and the other contained nicotine (0, 3.125, 6.25, 12.5, 25, 50 or 100 micro g/ml). The total amount of water and nicotine solution consumed was measured every three days for 16 days. MAO-B KO mice and WT mice consumed equal amounts of nicotine and exhibited comparable concentration-dependent nicotine preference and aversion over a period of 16 days. The data suggest that the absence of MAO-B impairs the ability of mice to habituate in the inescapable environment, but does not alter their nicotine intake.