Genes, time to first cigarette and nicotine dependence in a general population sample of young adults

A study on the prevalence of smoking habits among the student community in Aseer Region, Saudi Arabia

Objectives

A cross-sectional study was aimed to assess the prevalence of smoking habits among students at King Khalid University (KKU), Abha, KSA.

Methods

This was a cross-sectional study using a Modified Fagerstrom Tolerance Questionnaire (mFTQ), online survey was carried out among the students of KKU. This tool uses a five-point Likert scale for all seven questions, except one question on smoking during the first 2 h of the day.

Results

The prevalence of smoking among male students was 67% (n = 243) and females 33% (n = 122). Of the current cigarette smokers, 19% had a nicotine dependence score of ≥6 (high), 48% scored 4-6 (moderate) and 33% scored <4 (minimal). Association between mFTQ and the number of cigarettes per day (p < 0.001), first smoke of your cigarettes (p < 0.018), smoking in the morning (p < 0.007), and difficulty refraining from smoking in public areas (p < 0.000). The results of the current study recommend that cigarette smoking habits are a significant risk behavior among young students. The strength of this study signifies that most participants (62%) intend to quit if appropriately supported.

Conclusion

According to the findings of the current investigation, smoking was quite common among males. It raises the alarm about the critical need for adequate education to support health education initiatives, discourage teen smoking, and enhance health outcomes for the community.

Decreased anxiety-like behavior in a selectively bred high nicotine-preferring rat line

Genetic vulnerability contributes significantly to the individual variability observed in nicotine dependence. Selective breeding for sensitivity to a particular effect of abused drugs has produced rodent lines useful for studying genetic vulnerability to drug addiction. Previous research showed that anxiety-related personality traits are associated with nicotine dependence. Therefore, we examined the differences in anxiety-like behavior between a high nicotine-preferring rat line and their controls. At the beginning of the study, all rats, naïve to any drug, were exposed sequentially to open field arena, marble-burying and elevated plus-maze paradigms. In the second step, all rats received nicotine in drinking water for 7 weeks. Behavioral tests were rerun on the final 2 weeks of chronic nicotine treatment. Elevated plus-maze testings under basal condition and during chronic nicotine treatment showed that the time spent on the open arms, preference for being in the open arms, and the latency to enter the closed arms were higher, whereas open arm avoidance index was lower in nicotine-preferring rats compared to the controls. In the open field test, nicotine-preferring rats spent longer time in the central zone and excreted less fecal pellets; they buried less marbles in the marble-burying test. These findings indicate a lower level of anxiety-like behavior in nicotine-preferring rat line under basal conditions and during chronic nicotine treatment. We conclude that lower anxiety level in nicotine-preferring rat line is consistent with novelty-seeking personality type and may increase vulnerability to nicotine dependence in this rat line.

Biochemical and genetic biomarkers associated with nicotine dependence in Mexican smokers

Cigarette smoking remains an important health concern and is still a leading cause of preventable mortality. Nicotine is the substance responsible for sustained tobacco use and dependence. Identification of biomarkers underlying nicotine dependence behavior is important to identify people at risk for this dependence. In the present study, we identified biochemical and genetic biomarkers of nicotine dependence detected by the Fagerström Test for Nicotine Dependence (FTDN) in Mexican smokers. The nicotine metabolites nicotine-N'-oxide, trans-3'-hydroxycotinine-glucuronide (3HC-O-Gluc), and nicotine-N-Gluc (Gluc) were useful to differentiate nicotine-dependent from non-dependent subjects (p < .0001) with an area under the curve (AUC) of 0.7818. Genetic variants in CYP2A6, FMO3, and UGT2B7 (rs2431413, rs28363545, and rs7439326, respectively) were associated with nicotine dependence (p = .03, p = .01, p = .01, respectively). Variations in the enzymatic activity of CYP2A6 were associated with altered nicotine-N'-oxide and 3HC-O-Gluc levels. Decreased urinary levels of 3HC-O-Gluc and increased nicotine-N'-oxide were associated with a decrease in the functional activity of CYP2A6. A strong positive correlation was observed between the ratio of urinary 3HC/cotinine, a measure of CYP2A6 activity, and the levels of 3HC-O-Gluc (p < .0001, r = .6835), while a strong negative correlation was observed with nicotine-N'-oxide (p < .0001, r = .6522) in nicotine-dependent subjects. No correlations were observed in non-nicotine-dependent subjects. These data suggest that particular urinary nicotine metabolites and genetic variants involved in nicotine metabolism are useful to identify subjects with nicotine dependence in the Mexican population.

A mixed-method analysis of counterfactual thinking, negative event themes, and the transtheoretical model in a community sample of smokers

The transtheoretical model has been used as a model of behavior change for tobacco users. However, it does not account for perceptions of past behavior that may provide additional guidance toward smoking cessation. No studies have examined associations between the transtheoretical model, content themes of smoking experiences, and counterfactual thoughts (i.e. "If only. . .then. . ."). Mturk participants (N = 178; 47.8% female) completed measures of smoking attitudes, behavior, and stage and processes of change use. Participants described a past negative smoking event and an event-related counterfactual thought-listing task. Participants in the precontemplation stage endorsed fewer processes of change. Also, participants in the action stage reported significantly more counterfactuals about cravings (e.g. If only I could have controlled my urge to smoke. . .) inferring that they may be identifying cravings or urges as relevant barriers toward smoking cessation. Identifying these self-relevant thoughts may provide additional ways to address and overcome barriers toward achieving long-term smoking cessation.

Genetic architecture of four smoking behaviors using partitioned SNP heritability

BACKGROUND AND AIMS

Although genome-wide association studies have identified many loci that influence smoking behaviors, much of the genetic variance remains unexplained. We characterized the genetic architecture of four smoking behaviors using single nucleotide polymorphism (SNP) heritability (h²_SNP ). This is an estimate of narrow-sense heritability specifically estimating the proportion of phenotypic variation due to causal variants (CVs) tagged by SNPs.

DESIGN

Partitioned h²_SNP analysis of smoking behavior traits.

SETTING

UK Biobank.

PARTICIPANTS

UK Biobank participants of European ancestry. The number of participants varied depending on the trait, from 54 792 to 323 068.

MEASUREMENTS

Smoking initiation, age of initiation, cigarettes per day (CPD; count, log-transformed, binned and dichotomized into heavy versus light) and smoking cessation with imputed genome-wide SNPs.

FINDINGS

We estimated that, in aggregate, approximately 18% of the phenotypic variance in smoking initiation was captured by imputed SNPs [h²_SNP = 0.18, standard error (SE) = 0.01] and 12% [SE = 0.02] for smoking cessation, both of which were more than twice the previously reported estimates. Estimated age of initiation (h²_SNP  = 0.05, SE = 0.01) and binned CPD (h²_SNP  = 0.1, SE = 0.01) were substantially below published twin-based h² of 50%. CPD encoding influenced estimates, with dichotomized CPD h²_SNP  = 0.28. There was no evidence of dominance genetic variance for any trait.

CONCLUSION

A biobank study of smoking behavior traits suggested that the phenotypic variance explained by SNPs of smoking initiation, age of initiation, cigarettes per day and smoking cessation is modest overall.

Association Study of Opioid Receptor Delta-Type 1 (OPRD1) Gene Variants with Nicotine Dependence in an Iranian Population

Twins studies indicate that many individual factors are associated with genetic polymorphisms in tobacco use, dependence vulnerability, and the ability to quit smoking. Opioid receptor delta-type 1 (OPRD1) is one of the most important genes in the opioid pathway. Therefore, the current study aimed to investigate the association of variants located in the intron 1 of the OPRD1 gene, including rs2236857, rs2236855, and rs760589, with susceptibility to nicotine dependence among northern Iranians. DNA of 426 individuals, including 224 smokers and 202 healthy people, were extracted with the salting-out standard technique, qualified with Agarose gel, then quantified with Nanodrop, and finally genotyped by Amplification Refractory Mutation System (ARMS) PCR. All statistical analyses were performed by SNPAlyze version 8.1 and SPSS version 20. Results revealed no significant association of all three studied variants with the susceptibility to nicotine dependence in any models of inheritance. However, there were five haplotypes with an overall frequency higher than 0.05; no significant impact of any of them on nicotine dependence was observed. Altogether, rs2236857, rs2236855, and rs760589 were not associated with nicotine dependence among northern Iranians.

Expanding the genetic architecture of nicotine dependence and its shared genetics with multiple traits

Cigarette smoking is the leading cause of preventable morbidity and mortality. Genetic variation contributes to initiation, regular smoking, nicotine dependence, and cessation. We present a Fagerström Test for Nicotine Dependence (FTND)-based genome-wide association study in 58,000 European or African ancestry smokers. We observe five genome-wide significant loci, including previously unreported loci MAGI2/GNAI1 (rs2714700) and TENM2 (rs1862416), and extend loci reported for other smoking traits to nicotine dependence. Using the heaviness of smoking index from UK Biobank (N = 33,791), rs2714700 is consistently associated; rs1862416 is not associated, likely reflecting nicotine dependence features not captured by the heaviness of smoking index. Both variants influence nearby gene expression (rs2714700/MAGI2-AS3 in hippocampus; rs1862416/TENM2 in lung), and expression of genes spanning nicotine dependence-associated variants is enriched in cerebellum. Nicotine dependence (SNP-based heritability = 8.6%) is genetically correlated with 18 other smoking traits (rg = 0.40-1.09) and co-morbidities. Our results highlight nicotine dependence-specific loci, emphasizing the FTND as a composite phenotype that expands genetic knowledge of smoking.

The Intersection between Spliff Usage, Tobacco Smoking, and Having the First Joint after Waking

Cannabis users who are also tobacco smokers are more likely to exhibit cannabis dependence and psychosocial problems. However, there has been minimal research around various cannabis and tobacco mixing (spliff usage) behaviours and likeliness to smoke the first joint within an hour of waking, known colloquially as wake and bake. The time of first joint and spliff usage may be related as they are associated with the intersection of tobacco and cannabis use. Compared to non-morning cannabis users, morning users reported significantly more cannabis-related problems. Through a survey of US cannabis users, we test the association between various cannabis and spliff use behaviours and likeliness to smoke the first joint within an hour of waking. Compared to those who smoked tobacco and used spliffs, the following spliff use behaviour groups were less likely to have their first joint within 60 minutes after waking: those who smoked tobacco and used spliffs (95%CI: 0.605-0.988); those who never smoked tobacco and did not use spliffs (95%CI: 0.489-0.892); those who never smoked tobacco and used spliffs (95%CI:0.022-0.915). We provided possible explanations for our results and suggested further research to better understand findings, important given expanding US cannabis markets.

A mixed-effects location scale model for time-to-event data: A smoking behavior application

In general, mixed-effects location scale models (MELS) allow assessment of within-person and between-person variability with time-to-event data for outcomes that follow a normal or ordinal distribution. In this article, we extend the mixed-effects location scale model to time-to-event data in relation to smoking data. Better understanding of the time-graded within-person variability of factors involved in nicotine dependence can be helpful to researchers in their efforts to fine-tune smoking cessation programs. We illustrate the MELS model with data on time to first cigarette measured every day for 7 days in smokers randomized to two groups: a) those asked to keep smoking, or b) those asked to stop. Our results show that some individuals remain very stable in their time to first cigarette over the week, while others show variable patterns. The stable individuals smoked every day, did not smoke immediately upon waking, and were all in the group asked to keep smoking. Conversely, the variable individuals had at least one day during which they did not smoke, other days during which they smoked within the first 5 min of waking, and they were almost all in the group asked to quit smoking. These findings suggested that MELS have the potential to provide insights on how people try to stop smoking. More importantly, this model can be applied to other clinically important outcomes such as time to relapse in a range of cessation programs.

Time to First Cigarette and Self-Reported Health Among US Adult Smokers

Background:

Numerous studies have reported that shorter time to first cigarette (TTFC) is linked to elevated risk for smoking-related morbidity. However, little is known about the influence of early TTFC on self-reported health among current smokers. Hence, the objective of this study was to examine the association between TTFC and self-reported health among US adult smokers.

Methods:

Data came from the 2012-2013 National Adult Tobacco Survey (NATS). Current smokers aged 18 years and older (N = 3323) were categorized into 2 groups based on TTFC: ≤ 5 minutes (n = 1066) and >5 minutes (n = 2257). Propensity score matching (PSM) was used to control selection bias.

Results:

After adjusting for sociodemographic and smoking behavior factors, current smokers with early TTFC had higher odds for poor health in comparison with current smokers with late TTFC in the prematching (adjusted odds ratio [AOR] = 1.65; 95% confidence interval [CI] = 1.31-2.08) and postmatching (AOR = 1.60; 95% CI = 1.22-2.09) samples.

Conclusions:

In conclusion, smokers with early TTFC were associated with increased risk of poor health in the United States. To reduce early TTFC, elaborate efforts are needed to educate people about harms of early TTFC and benefits of stopping early TTFC.

Income as a moderator of psychological stress and nicotine dependence among adult smokers

BACKGROUND

Perceived stress and psychological distress are associated with more cigarette craving and withdrawal, higher nicotine dependence, and less success during quit attempts. Low income smokers have disproportionately higher rates of smoking and may be particularly vulnerable to the effects of stress on smoking dependence. The aim of the current study was to assess if lower income smokers have a stronger association between stress and nicotine dependence than higher income smokers.

METHODS

Data were obtained from the Pennsylvania Adult Smoking Study, which included 351 daily smokers. Subjects completed PhenX Toolkit and other self-report measures of socioeconomic factors, the 10-item Perceived Stress Scale, Kessler Psychological Distress Scale (K6), Fagerstrom Test for Nicotine Dependence (FTND), and the Hooked on Nicotine Checklist (HONC). Moderation analyses using linear regression examined income-related differences in the association between stress and nicotine dependence.

RESULTS

Income groups were categorized by an annual household income of $50,000 based on visual-inspection of scatter plots of income by nicotine dependence. Compared to higher income smokers, lower income smokers had significantly higher mean levels of nicotine dependence on the FTND [3.74 vs. 4.79, p < 0.001], perceived stress [15.63 vs. 17.95, p = 0.004], and psychological distress [5.30 vs. 6.86, p = 0.001], respectively. There were interaction effects, such that lower income smokers had a strong, positive associations between FTND and perceived stress (B = -0.11, CI = -0.17 to -0.04, p = 0.002) and psychological distress (B = -0.13, CI = -0.25 to -0.02, p = 0.022) whereas no association was found in higher income smokers. No significant moderation effects were found for the HONC or when income groups were categorized by U.S. federal poverty level.

CONCLUSIONS

The results highlight that the relationship between increasing stress and FTND was found in lower but not higher income groups. Future research should examine socioeconomic, environmental and psychosocial factors that may facilitate increased smoking during stress-induced craving.

Earlier smoking after waking and the risk of asthma: a cross-sectional study using NHANES data

Background

Recent research shows that nicotine dependence conveys additional health risks above and beyond smoking behavior. The current study examines whether smoking within 5 min of waking, an indicator of nicotine dependence, is independently associated with asthma outcomes.

Methods

Data were drawn from five pooled cross-sectional waves (2005–14) of NHANES, and the final sample consisted of N = 4081 current adult smokers. Weighted logistic regressions were run examining the relationship between smoking within 5 min of waking and outcomes of lifetime asthma, past-year asthma, and having had an asthma attack in the past year. Control variables included demographics, smoking behavior, family history of asthma, depression, obesity, and secondhand smoking exposure.

Results

After adjusting for smoking behavior, smoking within 5 min was associated with an approximately 50% increase in the odds of lifetime asthma (OR = 1.46, p = .008) and past-year asthma (OR = 1.47, p = .024), respectively. After additionally adjusting for demographics and other asthma risk factors, smoking within 5 min of waking was associated with a four-fold increase in the odds of lifetime asthma (OR = 4.05, p = .015).

Conclusions

Smoking within 5 min of waking, an indicator of nicotine dependence, is associated with a significantly increased risk of lifetime asthma in smokers. These findings could be utilized in refining risk assessment of asthma among smokers.

Electronic supplementary material

The online version of this article (10.1186/s12890-018-0672-y) contains supplementary material, which is available to authorized users.

Item Response Theory analysis of Fagerström Test for Cigarette Dependence

INTRODUCTION

The Fagerström Test for Cigarette Dependence (FTCD) and the Heaviness of Smoking Index (HSI) are the gold standard measures to assess cigarette dependence. However, FTCD reliability and factor structure have been questioned and HSI psychometric properties are in need of further investigations. The present study examined the psychometrics properties of the FTCD and the HSI via the Item Response Theory.

METHODS

The study was a secondary analysis of data collected in 862 Italian daily smokers. Confirmatory factor analysis was run to evaluate the dimensionality of FTCD. A Grade Response Model was applied to FTCD and HSI to verify the fit to the data. Both item and test functioning were analyzed and item statistics, Test Information Function, and scale reliabilities were calculated. Mokken Scale Analysis was applied to estimate homogeneity and Loevinger's coefficients were calculated.

RESULTS

The FTCD showed unidimensionality and homogeneity for most of the items and for the total score. It also showed high sensitivity and good reliability from medium to high levels of cigarette dependence, although problems related to some items (i.e., items 3 and 5) were evident. HSI had good homogeneity, adequate item functioning, and high reliability from medium to high levels of cigarette dependence. Significant Differential Item Functioning was found for items 1, 4, 5 of the FTCD and for both items of HSI.

CONCLUSIONS

HSI seems highly recommended in clinical settings addressed to heavy smokers while FTCD would be better used in smokers with a level of cigarette dependence ranging between low and high.

Nicotine dependence is associated with functional variation in FMO3, an enzyme that metabolizes nicotine in the brain

A common haplotype of the flavin-containing monooxygenase gene FMO3 is associated with aberrant mRNA splicing, a twofold reduction in in vivo nicotine N-oxidation and reduced nicotine dependence. Tobacco remains the largest cause of preventable mortality worldwide. CYP2A6, the primary hepatic nicotine metabolism gene, is robustly associated with cigarette consumption but other enzymes contribute to nicotine metabolism. We determined the effects of common variants in FMO3 on plasma levels of nicotine-N-oxide in 170 European Americans administered deuterated nicotine. The polymorphism rs2266780 (E308G) was associated with N-oxidation of both orally administered and ad libitum smoked nicotine (P⩽3.3 × 10-5 controlling for CYP2A6 genotype). In vitro, the FMO3 G308 variant was not associated with reduced activity, but rs2266780 was strongly associated with aberrant FMO3 mRNA splicing in both liver and brain (P⩽6.5 × 10-9). Surprisingly, in treatment-seeking European American smokers (n=1558) this allele was associated with reduced nicotine dependence, specifically with a longer time to first cigarette (P=9.0 × 10-4), but not with reduced cigarette consumption. As N-oxidation accounts for only a small percentage of hepatic nicotine metabolism we hypothesized that FMO3 genotype affects nicotine metabolism in the brain (unlike CYP2A6, FMO3 is expressed in human brain) or that nicotine-N-oxide itself has pharmacological activity. We demonstrate for the first time nicotine N-oxidation in human brain, mediated by FMO3 and FMO1, and show that nicotine-N-oxide modulates human α4β2 nicotinic receptor activity in vitro. These results indicate possible mechanisms for associations between FMO3 genotype and smoking behaviors, and suggest nicotine N-oxidation as a novel target to enhance smoking cessation.

CYP2A6 metabolism in the development of smoking behaviors in young adults

Cytochrome P450 2A6 (CYP2A6) encodes the enzyme responsible for the majority of nicotine metabolism. Previous studies support that slow metabolizers smoke fewer cigarettes once nicotine dependent but provide conflicting results on the role of CYP2A6 in the development of dependence. By focusing on the critical period of young adulthood, this study examines the relationship of CYP2A6 variation and smoking milestones. A total of 1209 European American young adults enrolled in the Collaborative Study on the Genetics of Alcoholism were genotyped for CYP2A6 variants to calculate a previously well-validated metric that estimates nicotine metabolism. This metric was not associated with the transition from never smoking to smoking initiation nor with the transition from initiation to daily smoking (P > 0.4). But among young adults who had become daily smokers (n = 506), decreased metabolism was associated with increased risk of nicotine dependence (P = 0.03) (defined as Fagerström Test for Nicotine Dependence score ≥4). This finding was replicated in the Collaborative Genetic Study of Nicotine Dependence with 335 young adult daily smokers (P = 0.02). Secondary meta-analysis indicated that slow metabolizers had a 53 percent increased odds (OR = 1.53, 95 percent CI 1.11-2.11, P = 0.009) of developing nicotine dependence compared with normal metabolizers. Furthermore, secondary analyses examining four-level response of time to first cigarette after waking (>60, 31-60, 6-30, ≤5 minutes) demonstrated a robust effect of the metabolism metric in Collaborative Study on the Genetics of Alcoholism (P = 0.03) and Collaborative Genetic Study of Nicotine Dependence (P = 0.004), illustrating the important role of this measure of dependence. These findings highlight the complex role of CYP2A6 variation across different developmental stages of smoking behaviors.

Adult interest in using a hypothetical modified risk tobacco product: findings from wave 1 of the Population Assessment of Tobacco and Health Study (2013-14)

BACKGROUND AND AIMS

The US Family Smoking Prevention and Tobacco Control Act provides a pathway for manufacturers to market a modified risk tobacco product (MRTP). This study examines socio-demographic and tobacco use correlates of interest in a hypothetical MRTP in a nationally representative sample of US adults.

DESIGN

Cross sectional wave 1 data from the 2013-14 Population Assessment of Tobacco and Health (PATH) Study.

SETTING

Household Audio-Computer Assisted Self-Interviews of US adults conducted in 2013-14.

PARTICIPANTS

A total of 32 320 civilian, non-institutionalized adults in the United States.

MEASUREMENTS

Interest in using a hypothetical MRTP ('If a tobacco product made a claim that it was less harmful to health than other tobacco products, how likely would you be to use that product?'), socio-demographics, tobacco use history and mental health and substance use problems. All estimates were weighted.

FINDINGS

Overall, 16.7% [95% confidence interval (CI) = 16.28, 17.18] of US adults reported interest in a hypothetical MRTP. Tobacco use was associated significantly with interest in a hypothetical MRTP, with interest most common among current established smokers (54.4%; 95% CI = 53.31, 55.39) and least common among never tobacco users (3.0%; 95% CI = 2.49, 3.55). Interest in a hypothetical MRTP was associated with experimental e-cigarette use among current experimental, current established and former smokers. Among non-smokers, race, age, education and substance use were associated with interest in using a hypothetical MRTP.

CONCLUSIONS

Among adults in the United States, interest in using a hypothetical modified risk tobacco product is low overall, and highest among current experimental and established smokers. A small percentage of non-smokers are interested in using a hypothetical hypothetical modified risk tobacco product.

Examination of the Involvement of Cholinergic-Associated Genes in Nicotine Behaviors in European and African Americans

Introduction

Cigarette smoking is a physiologically harmful habit. Nicotinic acetylcholine receptors (nAChRs) are bound by nicotine and upregulated in response to chronic exposure to nicotine. It is known that upregulation of these receptors is not due to a change in mRNA of these genes, however, more precise details on the process are still uncertain, with several plausible hypotheses describing how nAChRs are upregulated. We have manually curated a set of genes believed to play a role in nicotine-induced nAChR upregulation. Here, we test the hypothesis that these genes are associated with and contribute risk for nicotine dependence (ND) and the number of cigarettes smoked per day (CPD).

Methods

Studies with genotypic data on European and African Americans (EAs and AAs, respectively) were collected and a gene-based test was run to test for an association between each gene and ND and CPD.

Results

Although several novel genes were associated with CPD and ND at P < 0.05 in EAs and AAs, these associations did not survive correction for multiple testing. Previous associations between CHRNA3, CHRNA5, CHRNB4 and CPD in EAs were replicated.

Conclusions

Our hypothesis-driven approach avoided many of the limitations inherent in pathway analyses and provided nominal evidence for association between cholinergic-related genes and nicotine behaviors.

Implications

We evaluated the evidence for association between a manually curated set of genes and nicotine behaviors in European and African Americans. Although no genes were associated after multiple testing correction, this study has several strengths: by manually curating a set of genes we circumvented the limitations inherent in many pathway analyses and tested several genes that had not yet been examined in a human genetic study; gene-based tests are a useful way to test for association with a set of genes; and these genes were collected based on literature review and conversations with experts, highlighting the importance of scientific collaboration.

Relationship between Personality Traits and Nicotine Dependence in Male and Female Smokers of African-American and European-American Samples

AIMS

Personality characteristics are linked to nicotine dependence (ND). It remains unclear whether these factors differ across African-American (AA) and European-American (EA) male and female smokers. This study was aimed to determine the relationship between personality traits and smoking status, as well as the degree of ND, in AA and EA male and female samples.

METHODS

A total of 5,040 participants (AA: N = 3,737, female = 54.31%; EA: N = 1,313, female = 64.51%) were included in this study, with 2,474 smokers and 2,566 non-smokers. The measures used in this study included five dimensions of personality by the NEO-personality inventory-revised (neuroticism, extraversion, agreeableness, openness to experience, and conscientiousness), Fagerström test for ND, and drive subscale of the ND Syndrome Scale (NDSS).

RESULTS

In the AA sample, neuroticism was significantly associated with a higher risk of smoking [odds ratio (OR) = 1.057; 95% confidence interval (CI) 1.032, 1.083; p < 0.0001], and conscientiousness was significantly associated with decreased risk of smoking (OR = 0.936; 95% CI 0.912, 0.961; p < 0.0001). In the EA sample, higher neuroticism was associated with increased risk of being a current smoker (OR = 1.058; 95% CI 1.013, 1.104; p = 0.0105). Furthermore, we found that a lower level of neuroticism and higher level of conscientiousness were associated with the severity of ND in both the AA and EA samples and a broader range of personality factors were involved in predicting the severity of ND in the AA samples. However, no differential association was detected between male and female smokers of both AA and EA samples.

CONCLUSION

There exist differential relationships between personality traits and the severity of ND in the AA and EA samples.

Developmental Changes in Genetic and Shared Environmental Contributions to Smoking Initiation and Subsequent Smoking Quantity in Adolescence and Young Adulthood

BACKGROUND

Few studies examining the genetic architecture of cigarette smoking have focused on adolescents or examined developmental changes in additive genetic, shared environment, and unique environmental influences on liability to initiate cigarette smoking and quantity of cigarettes smoked. The aim of this study was to add to the literature on liability to initiate and use cigarettes during adolescence using a nationally representative sample.

METHOD

Data for this study came from adolescent and young adult twin pairs (aged 14-33 years) from the National Longitudinal Study of Adolescent to Adult Health. We ran a series of developmental causal-contingent-common pathway models to examine whether additive genetic, shared, and unique environmental influences on liability to the initiation of cigarette use are shared with those on smoking quantity, and whether their contributions change across development.

RESULTS

We found evidence for a developmental shift in genetic and shared environmental contributions to cigarette use. Early in adolescence, genetic and environmental influences work independently on liability to cigarette smoking initiation and quantity of cigarettes smoked, but liability to these behaviors becomes correlated as individuals age into young adulthood.

CONCLUSIONS

These findings provide insight into the causal processes underlying the liability to smoke cigarettes. With age, there is greater overlap in the genetic and environmental factors that influence the initiation of cigarette smoking and quantity of cigarettes smoked.

Strain-dependent performance in nicotine-induced conditioned place preference

Nicotine addiction is most likely a result of a combination of factors including the rewarding effects of the drug; these effects, however, might be influenced by genetic background. Using a conditioned place preference (CPP) paradigm and 8 inbred mouse strains, we conducted an initial examination of the role of genetic background in the rewarding effects of nicotine. Following habituation and initial place preference test, inbred strains (A/J, BALB/cByJ, C3H/HeJ, C57BL/6J, CBA/J, DBA/1J, DBA/2J, and 129/SvEv) were trained and tested in CPP for nicotine (0.35 mg/kg). Although several strains (C57BL/6J, CBA/J, and 129/SvEv) showed nicotine-induced CPP, 1 strain (DBA/1J) showed conditioned place aversion (CPA), and other strains (A/J, BALB/cByJ, C3H/HeJ, and DBA/2J) did not show CPP. Overall, these results indicate that nicotine's rewarding effects tested in CPP are differentially affected by the genetic background, and this trait has a relatively high heritability (42%-57%). This initial investigation lays the foundation for future studies examining the genetic substrates of nicotine reward.

Predictors of the Nicotine Dependence Behavior Time to the First Cigarette in a Multiracial Cohort

BACKGROUND

The time to first cigarette of the day (TTFC) is a strong indicator of nicotine dependence behaviors such as nicotine uptake and quit success in young and older smokers. There are substantial differences in levels of nicotine dependence by race and ethnic group.

METHODS

Data from Wave III of the multiracial National Longitudinal Study of Adolescent Health were analyzed for young smokers between the ages of 21 and 28 (N = 1,425). Time to first cigarette data was compared between Hispanic, White, Black, Native American, and Asian smokers.

RESULTS

Black smokers were significantly more likely to smoke within 5min of waking than White, Hispanic, and Asian smokers. Lower personal income predicted smoking within 5min of waking for both White and Black smokers. For White smokers, increased number of cigarettes per day and increased years of smoking also predicted smoking within 5min of waking. The number of days smoked or number of cigarettes per day did not predict smoking within 5min of waking among smokers.

CONCLUSIONS

The higher prevalence of early TTFC among Blacks indicates increased nicotine and carcinogen exposure, and may help explain the increased lung cancer rates and failed cessation attempts among Black smokers. TTFC may be an important screening item, independent of cigarettes per day, for clinicians and interventions to identify those at highest risk for cessation failure and disease risk.

Varenicline, low dose naltrexone, and their combination for heavy-drinking smokers: human laboratory findings

RATIONALE

Heavy-drinking smokers constitute a sizeable and hard-to-treat subgroup of smokers, for whom tailored smoking cessation therapies are not yet available.

OBJECTIVES

The present study used a double-blind, randomized, 2 × 2 medication design, testing varenicline alone (VAR; 1 mg twice daily), low dose naltrexone alone (L-NTX; 25 mg once daily), varenicline plus naltrexone, and placebo for effects on cigarette craving and subjective response to alcohol and cigarettes in a sample (n = 130) of heavy-drinking daily smokers (≥10 cigarettes/day).

METHODS

All participants were tested after a 9-day titration period designed to reach a steady state on the target medication. Testing was completed at 12 h of nicotine abstinence, after consuming a standard dose of alcohol (target breath alcohol concentration = 0.06 g/dl) and after smoking the first cigarette of the day.

RESULTS

The combination of VAR + L-NTX was superior to placebo, and at times superior to monotherapy, in attenuating cigarette craving, cigarette and alcohol "high," and in reducing ad-lib consumption of both cigarettes and alcohol during the 9-day medication titration period.

CONCLUSIONS

These preliminary findings indicate that clinical studies of the combination of VAR + L-NTX for heavy drinkers trying to quit smoking are warranted and may ultimately improve clinical care for this sizeable and treatment-resistant subgroup of smokers.

How smokers may react to cigarette taxes and price increases in Brazil: data from a national survey

BACKGROUND

Despite being the third largest tobacco producer in the world, Brazil has developed a comprehensive tobacco control policy that includes a broad restriction on both advertising and smoking in indoor public places, compulsory pictorial warning labels, and a menthol cigarette ban. However, tax and pricing policies have been developed slowly and only very recently were stronger measures implemented. This study investigated the expected responses of smokers to hypothetical price increases in Brazil.

METHODS

We analyzed smokers' responses to hypothetical future price increases according to sociodemographic characteristics and smoking conditions in a multistage sample of Brazilian current cigarette smokers aged≥14 years (n=500). Logistic regression analysis was used to examine the relationship between possible responses and different predictors.

RESULTS

In most subgroups investigated, smokers most frequently said they would react to a hypothetical price increase by taking up alternatives that might have a positive impact on health, i.e., they would "try to stop smoking" (52.3%) or "smoke fewer cigarettes" (46.8%). However, a considerable percentage responded that they would use alternatives that would reduce the effect of price increases, such as the same brand with lower cost (48.1%). After controlling for sex age group (14-19, 20-39, 40-59, and ≥60 years), schooling level (≥9 versus ≤9 years), number of cigarettes per day (>20 versus ≤20), and stage of change for smoking cessation (precontemplation, contemplation, and preparation), lower levels of dependence were positively associated with the response "I would try to stop smoking" (odds ratio [OR], 2.19). Young age was associated with "I would decrease the number of cigarettes" (OR, 3.44). A low schooling level was strongly associated with all responses.

CONCLUSIONS

Taxes and prices increases have great potential to stimulate cessation or reduction of cigarette consumption further among two important vulnerable populations of smokers in Brazil: young smokers and those of low educational level. The results from the present study also suggest that seeking illegal products may reduce the impact of increased taxes, but does not eliminate it.

The prevalence, predictors and associated health outcomes of high nicotine dependence using three measures among US smokers

AIMS

Using the Fagerström Test of Nicotine Dependence (FTND), the Heaviness of Smoking Index (HSI) and the time-to-first-cigarette (TTFC), this study estimated prevalence, evaluated optimal scale cut-offs, identified predictors and assessed potential impact on health, productivity and health-care use of high nicotine dependence among US smokers.

DESIGN, SETTING AND PARTICIPANTS

This cross-sectional study used 2011 National Health and Wellness Survey data (n = 50 000).

MEASUREMENTS

Nicotine dependence, demographic data, measures of health, productivity and health-care use and health attitudes were assessed.

FINDINGS

The prevalence of high nicotine dependence ranged from 23% (TTFC < 5 minutes) to 63.6% (TTFC < 30 minutes). Based on diagnostic accuracy, the cut-offs for high nicotine dependence using HSI and TTFC varied according to FTND cut-off: if FTND > 4, then HSI > 3 and TTFC < 30 minutes represented optimal cut-offs; if FTND > 5, HSI > 4 and TTFC < 5 minutes represented optimal cut-offs. Across all measures, high nicotine dependence was related significantly to being male, single, age 45-64 years and Caucasian; lower education; lack of health insurance; under/unemployment; comorbid respiratory or cardiovascular disease, diabetes or psychiatric illness; and lower rates of exercise and concern for weight control. Controlling for demographic variables and comorbid physical and psychiatric illness, high nicotine dependence, measured by FTND, HSI or TTFC, was associated significantly with reduced mental and physical quality of life, reduced work-place productivity and more health-care use.

CONCLUSIONS

High nicotine dependence is associated with lower quality of life, lower work productivity and higher health-care use. The Heaviness of Smoking Index and the time-to-first-cigarette can provide useful screening measures of nicotine dependence in clinical and research settings.

Time to first cigarette and lung cancer risk in Japan

BACKGROUND

Cigarette smoking is the major cause of lung cancer (LC). Although the time to first cigarette (TTFC) of the day is a distinct indicator of nicotine dependence, little information is available on its possible relation to LC.

PATIENTS AND METHODS

This case-control study includes a total of 1572 incident LC cases and 1572 non-cancer controls visiting for the first time the Aichi Cancer Center Hospital between 2001 and 2005. We estimated the odds ratio (OR) and 95% confidence interval (CI) for TTFC using a logistic regression model after adjustment for several potential confounders.

RESULTS

TTFC was inversely associated with the risk of LC. This association was consistent across histological subtypes of LC. For all LCs considered among ever smokers and after accurate allowance for smoking quantity and duration, besides other relevant covariates, compared with TTFC >60 min, the adjusted ORs were 1.08 (95% CI, 0.73-1.61) for TTFC of 31-60 min, 1.40 (0.98-2.01) for 6-30 min and 1.86 (1.28-2.71) for within 5 min (Ptrend, < 0.001). Statistically marginally significant heterogeneity by histological subtype was observed (Pheterogeneity, 0.002).

CONCLUSIONS

Nicotine dependence, as indicated by the TTFC, is associated with increased risk of LC and is therefore an independent marker of exposure to tobacco smoking.

Nicotine dependence and biochemical exposure measures in the second trimester of pregnancy

Introduction:

The Heaviness of Smoking Index (HSI) is validated to measure nicotine dependence in nonpregnant smokers, and in these smokers, mean salivary and serum cotinine levels are related by a ratio of 1.25. However, as nicotine metabolism increases during gestation, these findings may differ in pregnancy. We investigated the validity of HSI in pregnancy by comparing this with 3 biochemical measures; in a search for a less-invasive cotinine measure in pregnancy, we also explored the relationship between mean blood and salivary cotinine levels.

Methods:

Cross-sectional analyses using baseline data from the Smoking, Nicotine, and Pregnancy Trial. Participants were 16–46 years old, 12–24 weeks gestation, smoked more than 5 cigarettes per day, and had exhaled carbon monoxide (CO) readings of at least 8 ppm. Linear regression was used to examine correlations between HSI and blood cotinine and salivary cotinine and exhaled CO. Correlation between blood and salivary cotinine was investigated using linear regression through the origin.

Results:

HSI scores were associated with blood cotinine (R² = 0.20, n = 662, p < .001), salivary cotinine (R² = 0.11, n = 967, p < .001), and exhaled CO (R² = 0.13, n = 1,050, p < .001). Salivary and blood cotinine levels, taken simultaneously, were highly correlated (R² = 0.91, n = 628, p < .001) and the saliva:blood level ratio was 1.01 (95% CI 0.99–1.04).

Conclusions:

Correlations between HSI and biochemical measures in pregnancy were comparable with those obtained outside pregnancy, suggesting that HSI has similar validity in pregnant smokers. Salivary and blood cotinine levels are roughly equivalent in pregnant smokers.

The genetic correlation between cigarette smoking and alcohol drinking among Chinese adult male twins: an ordinal bivariate genetic analysis

BACKGROUND

Though multiple policies have been implemented, the cigarette control in China is still facing a great challenge. At the same time, alcohol drinking has increasingly become a public health problem. Considering cigarette smoking and alcohol drinking often co-occur, a few studies tested the covariance of these phenotypes. However, the genetic and environmental correlation between them among Chinese population has not been determined. The main aim of this study is to fill this gap.

METHODS

From the Chinese National Twin Registry, we obtained the data on cigarette smoking and alcohol drinking behaviors. The ordinal bivariate genetic analysis was performed to fit the categorical variables. After identifying the best decomposition among the Cholesky, common, and independent pathway model, we established the most parsimonious submodel.

RESULTS

The correlation between current tobacco and alcohol use could be explained by Cholesky model. The shared environmental variances for both phenotypes were dropped to construct the most parsimonious submodel. Furthermore, the most parsimonious submodel showed a moderate correlation (0.32, 95%CI=0.17-0.46) between the genetic components and a negligible non-shared environmental correlation.

CONCLUSION

As the first bivariate genetic analysis on current tobacco smoking and current alcohol drinking in China, this study suggested a common genetic vulnerability to tobacco and alcohol use in male twins. Further studies should be carried out to track the pertinent genes that are related to the comorbidity of smoking and drinking in Chinese population. Another urgent need is to recognize the behavior-specific environmental risk factors.

Time to first cigarette and serum cotinine levels in adolescent smokers: National Health and Nutrition Examination Survey, 2007-2010

INTRODUCTION

Nicotine dependence and uptake among adolescents remains challenging to characterize and measure. Among adults, a shorter time to the first cigarette after waking up in the morning (TTFC) has become increasingly recognized as an indicator of nicotine dependence because of its association with biological measures of nicotine exposure, smoking relapse, and failed cessation attempts. However, the relation between TTFC and these measures has not been studied among adolescents. This study explored the association between TTFC and cotinine among adolescent smokers.

METHODS

The study utilized 2007-2008 and 2009-2010 National Health and Nutrition Examination Survey (NHANES) data from 220 regular adolescent smokers between the ages of 12 and 19 who provided blood samples for cotinine evaluation. Regression modeling was conducted to determine whether TTFC predicts cotinine levels, a marker of nicotine uptake.

RESULTS

The time to first cigarette was significantly correlated with several smoking behaviors including number of cigarettes per day, time since last cigarette, and having a family member who smokes at home. Mean cotinine levels were more than 200 ng/ml in youths who smoked within 5 min after waking, compared with less than 34 ng/ml in youths who waited for more than 1 hr. In multiple regression models, a shorter time to first cigarette predicted higher cotinine levels after controlling for number of cigarettes per day and other factors. The TTFC was a predictor of cotinine for both male and female smokers.

CONCLUSION

The TTFC is a strong indicator of nicotine dependence in adolescents and could be an important component in screening for high-risk smoking and the development of tailored adolescent smoking intervention programs.

A systematic review of the A118G (Asn40Asp) variant of OPRM1 in relation to smoking initiation, nicotine dependence and smoking cessation

Candidate gene studies on smoking behaviors mainly focused on dopaminergic and serotonergic genes, but genes within the µ-opioid system might also be involved. The A118G variant within the OPRM1 gene has been most often examined in relation to smoking, yielding inconsistent findings. It is largely unknown which of the alleles increases susceptibility for smoking behaviors. The aim of this review was to merge findings of OPRM1 gene studies in relation to smoking behaviors and to elaborate on the underlying biological mechanism of the A118G variant. It appeared that A118 was more likely to increase susceptibility to smoking behaviors than 118G, especially with regard to nicotine dependence, but less with smoking initiation and cessation. The proposed functioning of the OPRM1 gene is further explained.

Psychosocial factors in adolescent nicotine dependence symptoms: a sample of high school juniors who smoke daily

Cross-sectionally examined seven theory-guided psychosocial factors associated with nicotine dependence symptoms in a representative self-report survey of 794 Washington State high school junior daily smokers (93% participation). Outcomes were four nicotine dependence symptoms. Results showed that low self-efficacy for quitting smoking and being around adults who smoke were associated with a 3.48-10.35 and a 1.47-1.77 times higher odds, respectively, of each of the four nicotine dependence symptoms. These results, needing replication in a longitudinal study, suggest that interventions designed to enhance self-efficacy to quit smoking and counter adult smoking influences might reduce adolescent nicotine dependence.

Alpha-5 and -3 nicotinic receptor gene variants predict nicotine dependence but not cessation: findings from the COMMIT cohort

Smoking many cigarettes per day (CPD) and short interval to first cigarette (TTF) after waking are two of the most heritable smoking phenotypes and comprise the Heavy Smoking Index (HSI). These phenotypes are often used as proxies for nicotine dependence (ND) and are associated with smoking cessation outcomes. Case-control and genome-wide association studies have reported links between single nucleotide polymorphisms (SNPs) in the alpha-5 and -3 nicotinic receptor subunit (CHRNA5 and CHRNA3) genes and CPD but few have examined TTF or cessation outcomes. In this study we longitudinally assessed 1301 European-American smokers at four time-points from 1988 to 2005. One CHRNA5 (rs16969968) and two CHRNA3 (rs1051703, rs6495308) SNPs were examined for their ability to predict smokers who "ever" reported ND based on three phenotypic classifications: (1) 25+ CPD, (2) TTF < 10 min, and (3) HSI ≥ 4. In a subsample of 1157 quit attempters, we also examined each SNP's ability to predict "ever" quitting for a period of >6 months. Demographically adjusted logistic regressions showed significant allelic and genotypic associations between all three SNPs and CPD but not TTF, HSI, or smoking cessation. Carriers of both the rs16969968-AA and rs6495308-TT genotypes had approximately twofold greater odds for ND defined using CPD or TTF. Results suggest nicotinic receptor variants are associated with greater odds of ND according to CPD and to a lesser extent TTF. Research examining the effect of nicotinic receptor genetic variation on ND phenotypes beyond CPD is warranted.

Biomarkers to optimize the treatment of nicotine dependence

The application of genomic medicine to the treatment of nicotine dependence holds great promise for revitalizing the steady decline in smoking rates witnessed in the USA over the past several decades. This paper examines the current knowledge base concerning the use of biomarkers to guide the selection of nicotine dependence treatments. First, we review the neurobiology of nicotine dependence and present evidence that supports its heritability. We then discuss the various studies of pharmacokinetic and pharmacodynamic genes related to therapeutic response. Current evidence suggests that biomarkers of genetic variability in both nicotine metabolism, referred to as the nicotine metabolite ratio, and dopamine genotypes may be useful for guiding treatment selection for nicotine dependence. Barriers to the translation of this research to clinical practice are discussed, as are directions for future research.

Development and reliability of the lifetime interview on smoking trajectories

INTRODUCTION

Assessments of lifetime smoking history are useful in many types of research including surveillance, epidemiology, prevention, intervention, and studies of genetic phenotypes and heritability. Because prospective assessment is impractical for most research, our objective was to develop a reliable retrospective measure of lifetime smoking history. This paper presents descriptive and test-retest reliability data on smoking history variables assessed using the Lifetime Interview on Smoking Trajectories (LIST).

METHODS

Data were collected on a birth cohort sample of 1,625 men and women (ages 34-44) from the Collaborative Perinatal Project. A subsample of 344 was invited to participate in a retest interview 4-8 weeks later and 220 participated. Indices of test-retest reliability were evaluated for smoking history variables, including: (a) early smoking experiences; (b) age at various smoking milestones, such as first puff, and progression to weekly and daily smoking; (c) smoking rate and time to first cigarette within initial, current, most recent, and heaviest phases; and (d) prolonged nonsmoking phases.

RESULTS

Responses to whether each of 5 major smoking milestones occurred were all highly reliable (κ = .78-.92), and of the 20 phase-specific variables assessed, more than half were reported at the highest level of reliability. None of the variables demonstrated low reliability.

CONCLUSIONS

Although retrospective reports have unavoidable limitations, our findings indicate that the LIST is a reliable instrument for assessing detailed retrospective smoking history data and can be used to add to the knowledge base of how patterns of use relate to a variety of outcomes of interest.

Major depression is a risk factor for shorter time to first cigarette irrespective of the number of cigarettes smoked per day: evidence from a National Population Health Survey

Introduction:

We assessed whether major depression (MD) predicts progression of nicotine dependence (ND) as measured by reduction in the time to first cigarette (TTFC) after waking and the roles of the number of cigarettes smoked per day (CPD) and stress as explanatory variables of this association.

Methods:

Ten years of follow-up data from the National Population Health Survey (NPHS) were used. The analyses were based on this nationally representative sample of the Canadian population who were over the age of 12 years in 1996 (n = 13,298). The NPHS included measures of MD and TTFC. Shorter TTFC was defined as TTFC within 5 min of waking. Heavy smoking (HS) was defined by smoking 20 or more CPD. Using proportional hazard models, unadjusted and adjusted hazard ratios (HRs) for shorter TTFC were estimated for those with and without MD.

Results:

The unadjusted HR for shorter TTFC among those with MD versus those without MD was 3.7 (95% CI: 2.6–5.3, p < .001). MD predicted onset of shorter TTFC even after adjustment for HS and tendency to smoke more under stress (HR: 1.7; 95% CI: 1.1–2.5, p = .02). When TTFC was defined using longer cutoffs (30 and 60 min), HS completely accounted for the effect of MD on TTFC onset.

Conclusions:

MD appears to be a risk factor for transition to shorter TTFC independent of effects of HS and the tendency to smoke more under stress. As MD is often modifiable, the above association points toward a preventive opportunity in relation to worsening of ND.

Nicotine dependence phenotype, time to first cigarette, and risk of head and neck cancer

BACKGROUND

A behavioral phenotype that characterizes nicotine dependence, the time to first cigarette after waking, is hypothesized to increase the risk of head and neck cancer.

METHODS

A case-control study of histologically confirmed head and neck cancer was conducted that included 1055 cases and 795 controls with a history of cigarette smoking.

RESULTS

The pack-years-adjusted odds ratio was 1.42 (95% confidence interval [95% CI], 1.02-1.99) for an interval of 31 minutes to 60 minutes to first cigarette after waking and 1.59 (95% CI, 1.19-2.11) for an interval of 1 minute to 30 minutes. The risk estimates were similar when smoking was modeled as total years, smoking status (current vs former), number of cigarettes smoked per day, years since quitting, and excess odds ratio. Findings were consistent for cancers of the floor of the mouth, palate, and pharynx.

CONCLUSIONS

Time to first cigarette is an indicator of increased nicotine dependence, smoke uptake, and risk of head and neck cancer. This high-risk group of individuals would benefit from targeted smoking interventions.

Strain-dependent effects of acute, chronic, and withdrawal from chronic nicotine on fear conditioning

The effects of nicotine on cognitive processes such as learning and memory may play an important role in the addictive liability of tobacco. However, it remains unknown whether genetic variability modulates the effects of nicotine on learning and memory. The present study characterized the effects of acute, chronic, and withdrawal from chronic nicotine administration on fear conditioning, somatic signs, and the elevated plus maze in 8 strains of inbred mice. Strain-dependent effects of acute nicotine and nicotine withdrawal on contextual fear conditioning, somatic signs, and the elevated plus maze were observed, but no association between the effects of acute nicotine and nicotine withdrawal on contextual fear conditioning were observed, suggesting that different genetic substrates may mediate these effects. The identification of genetic factors that may alter the effects of nicotine on cognition may lead to more efficacious treatments for nicotine addiction.

A latent class analysis of DSM-IV and Fagerström (FTND) criteria for nicotine dependence

BACKGROUND

Nicotine dependence is associated with considerable morbidity and mortality. Two predominant classification systems, the Diagnostic and Statistical Manual (DSM-IV) and Fagerström Test for Nicotine Dependence (FTND), have been used to measure liability to nicotine dependence, yet few studies have attempted to simultaneously examine both sets of criteria.

METHODS

Using a sample of 624 regular smoking individuals who are offspring of Vietnam Era Twin fathers ascertained for an offspring of twin study, we applied latent class analysis to the 7 DSM-IV and the 6 FTND criteria to classify individuals by their nicotine dependence symptom profiles. Post-hoc across-class comparisons were conducted using a variety of smoking-related variables and aspects of psychopathology. Whether a single class identified offspring at high genetic and environmental vulnerability was also investigated.

RESULTS

The cross-diagnosis kappa was .30. A 4-class solution fit these data best. The classes included a low DSM-low FTND class and a high DSM-high FTND class; a moderate DSM-moderate FTND class, which was distinguished by moderate levels of smoking and intermediate levels of comorbid psychopathology; and a light smoking-moderate FTND class consisting primarily of lighter smokers with a more recent onset of regular smoking. High genetic and environmental vulnerability to nicotine dependence was noted in all classes with no statistically significant across-class differences.

CONCLUSIONS

In general, the DSM-IV and FTND criteria performed similarly to define a continuum of risk for nicotine dependence. The emerging class of light smokers should be further investigated to assess whether they transition to another class or remain as such.

Changes in smokers' attitudes toward intended cessation attempts in Japan

BACKGROUND

Japan has the highest smoking prevalence among the G7 countries, and the Japanese government is expanding tobacco control measures, such as financial support for nicotine replacement therapy and cigarette price increases, to reduce smoking. In 2006, we examined intended quit attempts using hypothetical questions. Since then, a price increase for cigarettes has been proposed and has come closer to being realized.

OBJECTIVE

To examine attitude changes in intending to quit attempts according to the reinforcement of tobacco control policies and to clarify the attitudes toward the smoking policies under debate.

METHOD

In July 2006, a discrete choice experiment was performed in 616 current smokers. In January 2010, we conducted the same discrete choice experiment in 600 current smokers. In addition, we investigated attitudes toward increased cigarette price and amendments to the laws regulating the tobacco industry.

RESULTS

In general, between 2006 and 2010, the discrete choice experiment indicated that the smoking continuation rate decreased for highly dependent smokers and increased for low and moderately dependent smokers. Regarding individual measures, increases in tobacco price consistently persuaded smokers of all dependence levels to attempt to quit smoking, whereas factors such as risk information and a smoking ban were effective only for low-dependence smokers. Current smokers show less support for a price increase and legislation of health promotion than nonsmokers. Of current smokers, those with greater nicotine dependence support these policies less.

CONCLUSIONS

The shift of preference for intended attempts to quit is diverse according to nicotine dependence. These differences may be derived from the variations of their time and risk preference and their trust in the tobacco price policies.

The galanin receptor 1 gene associates with tobacco craving in smokers seeking cessation treatment

Craving for tobacco is a major challenge for people with nicotine dependence (ND) who try to quit smoking. Galanin (GAL) and its receptors (GALRs) can alter addiction-related behaviors and are therefore good candidates for modulators of behavioral parameters associated with smoking. We performed a genetic association study in 486 subjects (432 European American, EA) recruited for smoking cessation trials. Twenty-six candidate genes for ND-related phenotypes were selected based on the literature. Subjects were assessed using the Minnesota Withdrawal Scale (MWS), which included a specific item for craving, the Fagerström Scale of Nicotine Dependence (FTND), and other ND-related instruments. One single-nucleotide polymorphism (SNP) in GALR1, rs2717162, significantly associated with severity of craving in EA samples (p=6.48 × 10(-6)) and in the combined sample (p=9.23 × 10(-6)). Individuals with TT and TC genotypes had significantly higher craving scores than CC subjects. We also observed that SNPs in the CHRNA5 locus, rs16969968 and rs684513, which have been associated with ND-related phenotypes in previous studies, were nominally associated with FTND scores, although these results did not meet Bonferroni-adjusted criteria for experiment-wide significance. Our findings suggest that variation at GALR1 associates with differences in the severity of past craving for tobacco among smokers motivated to quit. Taken together with preclinical evidence, these results, if replicated, suggest that GAL and GALRs may be useful therapeutic targets for the pharmacological treatment of ND. Our results also confirm previously reported associations between variation at CHRNA5 and ND.

Dizziness and the genetic influences on subjective experiences to initial cigarette use

AIM

To examine individual differences in positive and negative subjective experiences to initial cigarette use.

DESIGN

Retrospective self-reports of initial subjective experiences were examined to estimate the genetic and environmental influences and the extent of their covariation across different effects.

PARTICIPANTS

Data was drawn from 2482 young adult same-and opposite sex twins- and siblings participating in the National Longitudinal Study of Adolescent Health.

MEASUREMENT

Subjective experiences were retrospectively collected using the Early Smoking Experience (ESE) questionnaire.

FINDINGS

Positive experiences evidenced moderate heritable contributions (40%, 95% CI: 0.22 to 0.56), as did an overall hedonic measure (34%, 95% CI: 0.22 to 0.46) and dizziness (34%, 95% CI: 0.15 to 0.52). Negative experiences evidenced small heritable contributions (13%, 95% CI: 0.00 to 0.36). Individual specific environmental influences were strong and accounted for the remaining proportion of observed variation in these experiences. Multivariate genetic modeling identified a moderately heritable underlying factor (37%, 95% CI: 0.22 to 0.52) that influenced the covariation of diverse subjective experiences and loaded most heavily on dizziness. Positive experiences also evidence residual genetic influences that were uncorrelated with other subjective experiences.

CONCLUSIONS

How a person experiences their initial few cigarettes is due to both heritable contributions and environmental experiences unique to the person. The covariation of diverse subjective experiences appears to be due to a heritable latent sensitivity to the chemicals contained in an average cigarette and is best indexed by dizziness.

Heritability of smoking, alcohol use, and psychological characteristics among adolescent twins in Qingdao, China

BACKGROUND

Previous studies of genetic and environmental influences on adolescent substance use have been limited to Western samples.

METHODS

This study assesses genetic and environmental contributions to cigarette smoking, alcohol use, and psychological variables (depression, anxiety, aggression, hostility) among 602 pairs of adolescent twins, 11 to 19 years old, in Qingdao, China.

RESULTS

Heritable influences were more pronounced for alcohol use than cigarette smoking. In univariate analyses, no heritable effects were found for depression or aggression, and modest heritability was found for anxiety. Hostility was relatively more heritable in girls than boys. Bivariate associations between substance use and psychological measures could be attributed to a combination of common genetic and environmental factors.

CONCLUSIONS

Among Chinese adolescents, experimentation with tobacco is familial, and experimentation with alcohol is heritable. The genetic and environmental architecture of hostility differs by gender. Consistency of univariate results with Western adolescent samples appears limited to the alcohol use measures.

Time to first cigarette after waking predicts cotinine levels

There is wide variability in cotinine levels per cigarette smoked. We hypothesized that in addition to smoking frequency, other behavioral measures of nicotine dependence, such as the time to first cigarette after waking, are associated with cotinine levels. To test this hypothesis, we measured plasma and urinary cotinine in a community-based study of 252 black and white daily cigarette smokers. Among one pack per day smokers, plasma cotinine levels varied from 16 to 1,180 ng/mL, a 74-fold difference. Two nicotine dependence phenotypes were discerned by time after waking. Subjects in the "low" dependent phenotype smoked >30 minutes after waking and nearly all smoked < or =20 cigarettes per day. Cotinine levels increased linearly with cigarette consumption in this group. Subjects in the "high" dependent phenotype smoked < or =30 minutes after waking but had a wide range in the frequency of daily cigarettes (6-70). Compared with the low dependent phenotype, there were relatively small differences in cotinine by cigarette frequency with evidence of a plateau effect in heavy smokers ( approximately 30). After adjusting for cigarette frequency, the levels of cotinine by time to first cigarette were as follows: < or =5 minutes, 437 [95% confidence limits (CL), 380-494]; 6 to 30 minutes, 352 (95% CL, 291-413), 31 to 60 minutes, 229 (95% CL, 140-317), and >60 minutes, 215 (95% CL, 110-321). Similar findings were observed for urinary cotinine. These findings suggest that the time to first cigarette is a strong predictor of nicotine uptake and should be considered in the design of smoking interventions.

Do smokers know what we're talking about? The construct validity of nicotine dependence questionnaire measures

Few studies have examined whether nicotine dependence self-report questionnaires can predict specific behaviors and symptoms at specific points in time. The present study used data from a randomized clinical trial (N = 608; M. E. Piper et al., 2007) to assess the construct validity of scales and items from 3 nicotine dependence measures: the Fagerström Test for Nicotine Dependence (T. F. Heatherton, L. T. Kozlowski, R. C. Frecker & K.-O. Fagerström, 1991), the Nicotine Dependence Syndrome Scale (S. Shiffman, A. J. Waters, & M. Hickcox, 2004), and the Wisconsin Inventory of Smoking Dependence Motives (M. E. Piper et al., 2004). Scales from these measures were used to predict participants' reports on real-time measures of withdrawal symptoms and smoking behavior and retrospective self-report questionnaires to assess convergent and discriminative validity. The nicotine dependence measures' scales and items generally predicted the real-time measures of similar constructs, but the percent of variance accounted for was low. The nicotine dependence measures did, however, show evidence of discriminative validity. Thus, this study provides modest support for the construct validity of these nicotine dependence scales.

Do smokers of specialty and conventional cigarettes differ in their dependence on nicotine?

Specialty cigarettes, bidis and kreteks, have commonly been viewed by adolescent users as being less harmful than conventional cigarettes. Biochemical studies, however, have shown that the concentration and delivery of nicotine from these tobacco products are not insignificant. The current study tested whether the diagnosis and symptoms for nicotine dependence differed among conventional-only smokers (n=16 959), specialty-only smokers (n=313), and poly-tobacco smokers (n=1288) from the 2002 and 2003 National Surveys on Drug Use and Health. Compared with the specialty-only smokers, the conventional-only and poly-tobacco smokers were more dependent on nicotine, assessed by the Nicotine Dependence Syndrome Scale and a single item from the Fagerstrom Test for Nicotine Dependence. However, after accounting for differences in smoking frequency, the specialty-only smokers had significantly greater odds of being nicotine dependent than the conventional-only smokers. The reversed effect was primarily attributed to the specialty-only smokers who smoked less frequently, but reported a shorter time to their first cigarette. These findings suggest that the nicotine acquired from specialty cigarettes may be sufficient in yielding a sense of urgency to smoke.

Differential item functioning of the English and Chinese versions of the Fagerstrom Test for Nicotine Dependence

Different language versions of the Fagerstrom Test for Nicotine Dependence (FTND) have been developed, but no studies have evaluated measurement equivalence between the respective non-English and English versions. We investigated differential item functioning (DIF) of the English and Chinese versions using a multidimensional item response theory approach. A community sample of 409 American smokers completed the English version (n=241) and the Chinese version (n=168). Results indicated two correlated dimensions (morning and daytime nicotine dependence) of the FTND and one item (difficult to refrain) showing significant large DIF, suggesting respondents using the Chinese version were more likely to endorse this item and report more difficulty to refrain from smoking at various public places even after controlling for the nicotine dependence level. However, the impact of this DIF item was found negligible on the scale level, suggesting the acceptability of conducting scale-level analysis using both language versions. Further analysis revealed that the reliabilities of two dimensions did not meet the commonly accepted standard. Suggestions were made to improve scale reliabilities of the FTND.

A testable prognostic model of nicotine dependence

Individuals' dependence on nicotine, primarily through cigarette smoking, is a major source of morbidity and mortality worldwide. Many smokers attempt but fail to quit smoking, motivating researchers to identify the origins of this dependence. Because of the known heritability of nicotine-dependence phenotypes, considerable interest has been focused on discovering the genetic factors underpinning the trait. This goal, however, is not easily attained: no single factor is likely to explain any great proportion of dependence because nicotine dependence is thought to be a complex trait (i.e., the result of many interacting factors). Genomewide association studies are powerful tools in the search for the genomic bases of complex traits, and in this context, novel candidate genes have been identified through single nucleotide polymorphism (SNP) association analyses. Beyond association, however, genetic data can be used to generate predictive models of nicotine dependence. As expected in the context of a complex trait, individual SNPs fail to accurately predict nicotine dependence, demanding the use of multivariate models. Standard approaches, such as logistic regression, are unable to consider large numbers of SNPs given existing sample sizes. However, using Bayesian networks, one can overcome these limitations to generate a multivariate predictive model, which has markedly enhanced predictive accuracy on fitted values relative to that of individual SNPs. This approach, combined with the data being generated by genomewide association studies, promises to shed new light on the common, complex trait nicotine dependence.

Time to first cigarette in the morning as an index of ability to quit smoking: implications for nicotine dependence

An inability to maintain abstinence is a key indicator of tobacco dependence. Unfortunately, little evidence exists regarding the ability of the major tobacco dependence measures to predict smoking cessation outcome. This paper used data from four placebo-controlled smoking cessation trials and one international epidemiological study to determine relations between cessation success and the Fagerström Test for Nicotine Dependence (FTND), the Heaviness of Smoking Index, the Nicotine Dependence Syndrome Scale, and the Wisconsin Inventory of Smoking Dependence Motives. Results showed that much of the predictive validity of the FTND could be attributed to its first item, time to first cigarette in the morning, and this item had greater validity than any other single measure. Thus the time-to-first-cigarette item appears to tap a pattern of heavy, uninterrupted, and automatic smoking and may be a good single-item measure of nicotine dependence.