Risk factors for tobacco dependence in adolescent smokers

The role of β-Nicotyrine in E-Cigarette abuse liability I: Drug Discrimination

Background

β-Nicotyrine (β-Nic) is a unique minor alkaloid constituent in electronic nicotine delivery systems (ENDS) that is derived from nicotine (Nic) degradation and can reach 25% of Nic concentrations in ENDS aerosol. β-Nic slows Nic metabolism and prolongs systemic Nic exposure, which may alter the discriminability of Nic. The present study sought to examine β-Nic has interoceptive effects itself, and if it alters the subjective effects ENDS products within a drug-discrimination paradigm.

Methods

The pharmacodynamics of β-Nic were examined in vitro, and a nicotine discrimination paradigm was used to determine if β-Nic (0 - 5.0 mg/kg) shares discriminative stimulus properties with Nic (0.2 mg/kg) in male (n = 13) and female (n = 14) rats after 10- & 60-min β-Nic pretreatment delays. A second group of rats was trained to discriminate β-Nic and Nornicotine (Nornic) from saline to determine if β-Nic alone has interoceptive properties and whether they are similar to Nornic.

Results

β-Nic had similar binding affinity and efficacy at the α4β2 nicotinic receptor subtype as Nornic, ~50% of Nic efficacy. However, β-Nic only weakly substituted for Nic during substitution testing in female rats, but not males, whereas Nornic fully substituted for Nic. Combination testing at the 10 and 60-min pretreatment intervals showed that β-Nic dose-dependently increased the duration of nicotine's discriminative stimulus effects, especially at the 60-min delay. Drug naïve rats could reliably discriminate Nornic, but not β-Nic, from Sal.

Conclusion

β-Nic increased and prolonged the interoceptive stimulus properties of Nic, suggesting it may alter to the abuse liability of ENDS through its ability to slow Nic metabolism.

Early developmental risks for tobacco addiction: A probabilistic epigenesis framework

Considerable progress has been made in elucidating the relationships between early life psychobiological and environmental risk factors and the development of tobacco addiction. However, a comprehensive understanding of the heterogeneity in tobacco addiction phenotypes requires integrating research findings. The probabilistic epigenesis meta-theory offers a valuable framework for this integration, considering systemic, multilevel, developmental, and evolutionary perspectives. In this paper, we critically review relevant research on early developmental risks associated with tobacco addiction and highlight the integrative heuristic value of the probabilistic epigenesis framework for this research. For this, we propose a four-level systems approach as an initial step towards integration, analyzing complex interactions among different levels of influence. Additionally, we explore a coaction approach to examine key interactions between early risk factors. Moreover, we introduce developmental pathways to understand interindividual differences in tobacco addiction risk during development. This integrative approach holds promise for advancing our understanding of tobacco addiction etiology and informing potentially effective intervention strategies.

Alcohol and Nicotine Use among Adolescents: An Observational Study in a Sicilian Cohort of High School Students

In recent years, the mode of alcoholic intake known as binge drinking (BD) has become a common practice, especially among adolescents who, due to socio-environmental motives, tend to reach a rapid state of drunkenness. This drunkeness leads to alterations in brain areas responsible for executive functions and cognitive processes, as well as to the genesis of factors that predispose to lasting addiction. Likewise, nicotine leads to a comparable degree of addiction. On this basis, the aim of this research was to evaluate, on a cohort of 349 high school students (15−17 years old) in the province of Palermo, the following: (I) the drinking model of alcoholic beverages; (II) the use of nicotine and the degree of dependence; (III) the correlation between the consumption of alcoholic beverages and the use of nicotine. We employed the AUDIT-C test and the Fagerström test, two valid and standard instruments, in order to assess alcohol and nicotine use, respectively. Statistical analysis of the data showed that male and female students consumed alcohol prominently in a BD mode (77.2%, audit score (AS) 3.497, confidence interval (CI) 3.206−3.788; 69.6%, AS 2.793, CI 2.412−3.274) and nicotine (41.5%, Fagerström score (FS) 3.882, CI 3.519−4.245; 28%, FS 3.286, CI 2.547−4.024). Furthermore, a positive correlation between alcohol consumption and nicotine use was found for male (r = 0.6798, p < 0.0001) and female (r = 0.6572, p < 0.0001) students. This study provided further insights into the use of legal substances of abuse in adolescents, evidencing the obvious need for the promotion of specific school educational programs aimed at the wellbeing of youth populations.

Multifactorial Etiology of Adolescent Nicotine Addiction: A Review of the Neurobiology of Nicotine Addiction and Its Implications for Smoking Cessation Pharmacotherapy

Nicotine is the primary pharmacologic component of tobacco, and its highly addictive nature is responsible for its widespread use and significant withdrawal effects that result in challenges to smoking cessation therapeutics. Nicotine addiction often begins in adolescence and this is at least partially attributed to the fact that adolescent brain is most susceptible to the neuro-inflammatory effects of nicotine. There is increasing evidence for the involvement of microglial cells, which are the brain's primary homeostatic sensor, in drug dependence and its associated behavioral manifestations particularly in the adolescent brain. A hallmark of neuro-inflammation is microglial activation and activation of microglia by nicotine during adolescent development, which may result in long-term addiction to nicotine. This non-systematic review examines multifactorial etiology of adolescent nicotine addiction, neurobiology of nicotine addiction and the potential mechanisms that underlie the effects of nicotine on inflammatory signaling in the microglia, understanding how nicotine affects the adolescent brain. We speculate, that modulating homeostatic balance in microglia, could have promising therapeutic potential in withdrawal, tolerance, and abstinence-related neural adaptations in nicotine addiction, in the adolescent brain. Further, we discuss nicotine addiction in the context of the sensitization-homeostasis model which provides a theoretical framework for addressing the potential role of microglial homeostasis in neural adaptations underlying nicotine abuse.

The reinforcement threshold and elasticity of demand for nicotine in an adolescent rat model of depression

BACKGROUND

The Food and Drug Administration (FDA) is considering setting a nicotine standard for tobacco products to reduce their addictiveness. Such a standard should account for the apparent greater vulnerability to nicotine addiction in some subpopulations, such as adolescents with depression. The present study examined whether the reinforcement threshold and elasticity of demand (i.e., reinforcing efficacy) for nicotine in a genetic inbred rat model of depression (Flinders Sensitive Line [FSL]) differs from an outbred control strain.

METHODS

Acquisition of nicotine self-administration (NSA) across a wide range of nicotine doses was measured in both FSL and Sprague-Dawley (SD) control adolescent rats. At the highest dose, elasticity of demand was also measured. Nicotine pharmacokinetics was examined to determine whether it might modulate NSA, as it does smoking in humans.

RESULTS

FSL rats acquired self-administration quicker and showed more inelastic demand (greater reinforcing efficacy) than SDs at the highest unit dose. However, there was no strain difference in the reinforcement threshold of nicotine. FSL rats exhibited faster nicotine clearance, larger volume of distribution, and lower plasma and brain nicotine concentrations. However, these differences were not consistently related to strain differences in NSA measures.

CONCLUSION

These findings are consistent with studies showing greater dependence and reinforcing efficacy of cigarettes in smokers with depression and those with relatively fast nicotine metabolism. However, these findings also suggest that a nicotine standard to reduce initiation of tobacco use should be similarly effective in both the general adolescent population and those with depression.

Understanding the implications of the biobehavioral basis of nicotine addiction and its impact on the efficacy of treatment

INTRODUCTION

Tobacco use remains the leading cause of preventable death in the United States. There are efficacious behavioral and pharmacological options for smoking cessation including three FDA approved therapies - nicotine replacement therapy, varenicline and bupropion. Nevertheless, uptake of smoking cessation treatments continues to be poor and there is a need for novel smoking cessation treatments. Areas covered: This article reviews the biobehavioral basis of nicotine addiction, its implications for smoking cessation treatments, the various neurotransmitter systems involved in nicotine addictive effects, and their potential therapeutic value. Included are discussions around the role of genetic factors in predicting response to pharmacotherapy and what we know about appropriate application of pharmacotherapy and behavioral interventions for tobacco use disorder. The evidence for harm reduction measures in individuals who are not willing or able to quit smoking is also reviewed. Expert commentary: Many neurotransmitter system targets have been investigated as a result of our understanding of the underlying neurobiology of tobacco use disorder, and there remain important targets that have yet to be fully explored. rTMS or combination therapies are proposed as possible novel strategies to improve smoking cessation.

Status and Future Directions of Preclinical Behavioral Pharmacology in Tobacco Regulatory Science

Behavioral pharmacology is a branch of the experimental analysis of behavior that has had great influence in drug addiction research and policy. This paper provides an overview of recent behavioral pharmacology research in the field of tobacco regulatory science, which provides the scientific foundation for the Food and Drug Administration Center for Tobacco Products (FDA CTP) to set tobacco control policies. The rationale and aims of tobacco regulatory science are provided, including the types of preclinical operant behavioral models it deems important for assessing the abuse liability of tobacco products and their constituents. We then review literature relevant to key regulatory actions being considered by the FDA CTP, including regulations over nicotine and menthol content of cigarettes, and conclude with suggesting some directions for future research. The current era of tobacco regulatory science provides great opportunities for behavioral pharmacologists to address the leading cause of preventable death and disease worldwide.

Nicotine Metabolite Ratio (NMR) Prospectively Predicts Smoking Relapse: Longitudinal Findings From ITC Surveys in Five Countries

INTRODUCTION

The ratio of trans 3'-hydroxycotinine (3HC) to cotinine (nicotine metabolite ratio [NMR]) is a biomarker of the rate of nicotine metabolism, with higher NMR indicating faster metabolism. Higher NMR has been found to be associated with higher daily cigarette consumption and less success stopping smoking in cessation trials. This study examines differences in NMR among population-based samples of smokers in the five countries and explores the relationship between NMR and smoking abstinence.

METHODS

Participants (N = 874) provided saliva samples during International Tobacco Control (ITC) surveys in the United States, United Kingdom, Mauritius, Mexico, and Thailand conducted in 2010/2011 with follow-up surveys in 2012/2013. When all samples were received, they were sent to a common laboratory for analysis using liquid chromatography and tandem mass spectroscopy.

RESULTS

There was significant variation in NMR across countries (F = 15.49, p < .001). Those who reported smoking at follow-up had a mean NMR of 0.32, compared to a mean NMR of 0.42 in participants who reported that they had stopped (F = 8.93; p = .003). Higher mean NMR values were also associated with longer quit duration (p = .007). There was no substantial difference in NMR between current smokers who made a failed quit attempt and those who made no attempt-both had significantly lower NMR compared to those who quit and remained abstinent. Smokers with a higher NMR were more likely to report that they stopped smoking compared to those with a lower NMR (odds ratio = 2.67; 95% confidence interval: 1.25 to 5.68).

CONCLUSIONS

These results suggest faster nicotine metabolizers may be less likely to relapse following a quit attempt. This finding differs from results of clinical trials testing stop smoking medications, where slower metabolizers have been found to be more likely to maintain abstinence from smoking.

IMPLICATIONS

Results of this study suggest faster nicotine metabolizers may be less likely to relapse following a quit attempt. This finding differs from results of clinical trials testing stop smoking medications, where slower metabolizers have been found to be more likely to maintain abstinence from smoking.

The Association of Cigarette Smoking With Depression and Anxiety: A Systematic Review

BACKGROUND

Many studies report a positive association between smoking and mental illness. However, the literature remains mixed regarding the direction of this association. We therefore conducted a systematic review evaluating the association of smoking and depression and/or anxiety in longitudinal studies.

METHODS

Studies were identified by searching PubMed, Scopus, and Web of Science and were included if they: (1) used human participants, (2) were longitudinal, (3) reported primary data, (4) had smoking as an exposure and depression and/or anxiety as an outcome, or (5) had depression and/or anxiety as the exposure and smoking as an outcome.

RESULTS

Outcomes from 148 studies were categorized into: smoking onset, smoking status, smoking heaviness, tobacco dependence, and smoking trajectory. The results for each category varied substantially, with evidence for positive associations in both directions (smoking to later mental health and mental health to later smoking) as well as null findings. Overall, nearly half the studies reported that baseline depression/anxiety was associated with some type of later smoking behavior, while over a third found evidence that a smoking exposure was associated with later depression/anxiety. However, there were few studies directly supporting a bidirectional model of smoking and anxiety, and very few studies reporting null results.

CONCLUSIONS

The literature on the prospective association between smoking and depression and anxiety is inconsistent in terms of the direction of association most strongly supported. This suggests the need for future studies that employ different methodologies, such as Mendelian randomization (MR), which will allow us to draw stronger causal inferences.

IMPLICATIONS

We systematically reviewed longitudinal studies on the association of different aspects of smoking behavior with depression and anxiety. The results varied considerably, with evidence for smoking both associated with subsequent depression and anxiety, and vice versa. Few studies supported a bidirectional relationship, or reported null results, and no clear patterns by gender, ethnicity, clinical status, length to follow-up, or diagnostic test. Suggesting that despite advantages of longitudinal studies, they cannot alone provide strong evidence of causality. Therefore, future studies investigating this association should employ different methods allowing for stronger causal inferences to be made, such as MR.

Correlates of nicotine dependence among adolescent waterpipe smokers

INTRODUCTION

Waterpipe smoking is addictive and its use is increasing globally among youth, yet little is known about the factors associated with nicotine dependence (ND) among waterpipe smokers. We investigated the factors associated with ND symptoms among a sample of Lebanese adolescents who smoke a waterpipe.

METHODS

We collected data on factors potentially associated with ND (individual, socio-demographic, environmental, smoking patterns) among 160 current (past 30days) waterpipe smokers recruited from 8th and 9th school grades in Lebanon. We assessed the loss of autonomy over tobacco using the Hooked on Nicotine Checklist (HONC), ND using the International Classification of Diseases, 10th revision (ICD-10), and the number of ND symptoms endorsed.

RESULTS

Depressive symptoms, lower self-esteem, and having at least one sibling who smokes a waterpipe were associated with the presence of ND symptoms, while enrollment in public schools, smoking a waterpipe ≥30min per session, and believing that cigarette smoking is harmful to health were associated with endorsement of a higher number of ND symptoms. Smoking a whole waterpipe head without sharing and being in 9th grade in this study were associated with the presence and endorsement of a higher number of ND symptoms.

CONCLUSIONS

We identified specific social and psychological characteristics, waterpipe smoking patterns, and beliefs about harmful effects of smoking associated with the presence of ND among adolescent waterpipe smokers. Considering these factors when planning policies to prevent ND among waterpipe smokers is warranted.

Relationship between early symptoms of alcohol craving and binge drinking 2.5 years later

BACKGROUND

The first self-reported symptoms of nicotine dependence (e.g., as craving) can appear within days to weeks of the onset of occasional use, and the appearance of symptoms predicts future consumption and dependence. We sought to determine whether craving for alcohol occurs in early stages of adolescent alcohol use, and whether it predicts future binge drinking, a prevalent and problematic behavior.

METHODS

Longitudinal (30-month) four-wave study of 3415 students (M=12.5 years at baseline) from 29 German schools. Students reported five symptoms of alcohol craving on a scale developed based on well-validated measures for tobacco. Multilevel mixed-effects logistic regression was used to predict having five or more binge episodes by last follow-up, based on the number of symptoms reported before the first lifetime binge. Multiple imputation was used to address study drop-out.

RESULTS

At baseline, 23% reported at least one symptom, increasing to 54% at wave 4. Any report of symptoms at baseline was associated with frequency of alcohol use, being present in 100% of daily, 93% of weekly, 87% of monthly, 48% of infrequent drinkers, and 16% of ever drinkers reporting no current alcohol use. Moreover, symptoms at baseline independently predicted frequent binge drinking 2.5 years later, AOR=2.08 (95% CI 1.39, 3.11; p<0.001) among baseline never-bingers, after adjusting for covariates.

CONCLUSIONS

Some early-onset drinkers reported symptoms of alcohol craving and loss of control after minimal exposure to alcohol. If replicated, an early screener could be developed to identify those at risk for frequent binge drinking.

[Cigarette smoking initiation among Tunisian adolescents: Risk and protective factors]

BACKGROUND

Since smoking is a major public health problem among Tunisian teenagers, it is important to identify the underlying risk and protective factors associated with initiation of this behavior.

METHODS

A cross-sectional, school-based survey of students was conducted by the Tunisian Ministry of Health among a nationally representative sample of 4172 adolescents aged between 12 and 20 years attending public, private, and professional secondary schools across Tunisia who participated in the Survey of the Health of Tunisian adolescents in 2000. For data analysis, we first calculated crude odds ratios (OR) followed by calculating adjusted OR after using multivariate logistic regression models.

RESULTS

Almost one-third of respondents had already started smoking at an average age of 13 years, 6.4% among them smoked daily. Demographic vulnerabilities to smoking behavior were gender (boys more than girls), age and residence in urban areas and particularly in Greater Tunis and the North East. Familial and school factors were parental divorce, poor relationship with parents, poor integration into the peer group, and poor school investment. Psychological and behavioral factors were low self-esteem level and the occurrence of stressful life events, risk taking and alcohol consumption when there was no association with the depression, anxiety and body image. Protective factors against the experimental cigarettes were mainly sports and reading.

CONCLUSION

There are many factors associated with smoking behavior among adolescents. All of these predictors need to be considered in smoking prevention among Tunisian teenagers.

Intergenerational Patterns of Smoking and Nicotine Dependence Among US Adolescents

OBJECTIVES

We examined associations between parental and adolescent smoking and nicotine dependence in the United States.

METHODS

We used data from the 2004 to 2012 National Survey on Drug Use and Health, which ascertained smoking behaviors of 1 parent and 1 adolescent aged 12 to 17 years in 35 000 dyads. We estimated associations between parental and adolescent smoking behaviors, adjusted for covariates.

RESULTS

Parental current dependence was strongly associated with adolescents' lifetime smoking (adjusted odds ratio [AOR] = 2.96; 95% confidence interval [CI] = 2.47, 3.55), whereas parental current nondependent smoking (AOR = 2.26; 95% CI = 1.92, 2.67) and former smoking (AOR = 1.51; 95% CI = 1.31, 1.75) were less strongly associated. Only parental nicotine dependence was associated with adolescent nicotine dependence (AOR = 1.66; 95% CI = 1.00, 2.74). Associations between parental and adolescent smoking did not differ by race/ethnicity. Parents' education, marital status, and parenting and adolescents' mental health, beliefs about smoking, perception of schoolmates' smoking, and other substance use predicted adolescent smoking and dependence.

CONCLUSIONS

Reducing parental smoking would reduce adolescent smoking. Prevention efforts should encourage parental smoking cessation, improve parenting, address adolescent mental health, and reinforce adolescents' negative beliefs about smoking.

Patient and Provider Factors Associated With American Indian and Alaska Native Adolescent Tobacco Use Screening

INTRODUCTION

Tobacco use is the leading behavioral cause of death among adults 25 years or older. American Indian (AI) and Alaska Native (AN) communities confront some of the highest rates of tobacco use and of its sequelae. Primary care-based screening of adolescents is an integral step in the reduction of tobacco use, yet remains virtually unstudied. We examined whether delivery of tobacco screening in primary care visits is associated with patient and provider characteristics among AI/AN adolescents.

METHODS

We used a cross-sectional analysis to examine tobacco screening among 4757 adolescent AI/AN patients served by 56 primary care providers at a large tribally managed health system between October 1, 2011 and May 31, 2014. Screening prevalence was examined in association with categorical patient characteristics (gender, age, clinic visited, insurance coverage) and provider characteristics (gender, age, tenure) using multilevel logistic regressions with individual provider identity as the nesting variable.

RESULTS

Thirty-seven percent of eligible patients were screened. Gender of both providers and patients was associated with screening. Male providers delivered screening more often than female providers (odds ratio [OR] 1.6, 95% confidence interval [CI] 0.7-3.9). Male patients had 20% lower odds of screening receipt (OR 0.8, 95% CI 0.7-0.9) than female patients, independent of patient age and provider characteristics. Individual provider identity significantly contributed to variability in the mixed-effects model (variance component 2.2; 95% CI 1.4-3.4), suggesting individual provider effect.

CONCLUSIONS

Low tobacco screening delivery by female providers and the low receipt of screening among younger, male patients may identify targets for screening interventions.

Depressive Symptoms Delayed Quit Attempts and Shortened Abstinence in Young Smokers of the Hong Kong Youth Quitline

INTRODUCTION

Young smokers often report depressive symptoms while receiving smoking cessation counseling. This study examines time patterns in the quitting process among young smokers with or without notable depressive symptoms.

METHODS

The quitting trajectories of young smokers aged 12 to 25 (n = 578) who called the Youth Quitline in Hong Kong between March 2006 and May 2011 were recorded and analyzed through multiple telephone sessions over periods of up to 6 months. The time patterns of young smokers who had or did not have notable depressive symptoms were compared using nonparametric Kaplan-Meier methods with log-rank tests.

RESULTS

Among young smokers with low levels of nicotine dependence, those who had notable depressive symptoms were less likely to initiate a quit attempt within 28 days after their baseline telephone intervention (probability = .38 vs. .60; P value = .04). Furthermore, young smokers who had notable depressive symptoms were less likely to remain abstinent from smoking for 2 days after starting a quit attempt (probability = .50 vs. .64; P value = .012). Young adults aged 18 or above were more likely to relapse into smoking (adjusted HR = 1.50, 95% CI = 1.01, 2.22).

CONCLUSIONS

Depressive symptoms may delay young smokers from initiating quit attempts and shorten their abstinence. A baseline screening process is suggested for identifying youths with co-occurring depressive disorder and nicotine dependence. Further studies should examine a collaborative model of smoking cessation that involves both counselors and physicians in preventing young smokers from rapid relapses after they make quit attempts.

Pharmacogenetics of nicotine and associated smoking behaviors

This chapter summarizes genetic factors that contribute to variation in nicotine pharmacokinetics and nicotine's pharmacological action in the central nervous system (CNS), and how this in turn influences smoking behaviors. Nicotine, the major psychoactive compound in cigarette smoke, is metabolized by a number of enzymes, including CYP2A6, CYP2B6, FMOs, and UGTs, among others. Variation in the genes encoding these enzymes, in particular CYP2A6, can alter the rate of nicotine metabolism and smoking behaviors. Faster nicotine metabolism is associated with higher cigarette consumption and nicotine dependence, as well as lower quit rates. Variation in nicotine's CNS targets and downstream signaling pathways can also contribute to interindividual differences in smoking patterns. Binding of nicotine to neuronal nicotinic acetylcholine receptors (nAChRs) mediates the release of several neurotransmitters including dopamine and serotonin. Genetic variation in nAChRs, and in transporter and enzyme systems that leads to altered CNS levels of dopamine and serotonin, is associated with a number of smoking behaviors. To date, the precise mechanism underpinning many of these findings remains unknown. Considering the complex etiology of nicotine addiction, a more comprehensive approach that assesses the contribution of multiple gene variants, and their interaction with environmental factors, will likely improve personalized therapeutic approaches and increase smoking cessation rates.

Reciprocal associations between cigarette consumption and DSM-IV nicotine dependence criteria in adolescent smokers

AIMS

To examine the inter-relationships between cigarette consumption and DSM-IV nicotine dependence (ND) criteria from smoking onset in adolescence up to 7 years later, adjusting for alcohol consumption and DSM-IV alcohol dependence (AD) criteria.

DESIGN

A cohort drawn from grades 6-10 in an urban school system was interviewed five times at 6-month intervals (waves 1-5) and 4.5 years later (wave 6). A parent was interviewed three times.

SETTING

Chicago, Illinois.

PARTICIPANTS

Recent smokers (n = 409).

MEASUREMENTS

Structured household interviews ascertained number of cigarettes smoked, DSM-IV ND symptoms, drinks consumed, DSM-IV AD symptoms, and selected covariates. Reciprocal prospective associations between number of cigarettes smoked and ND criteria, controlling for time-varying alcohol consumption and dependence criteria, were examined with cross-lagged models.

FINDINGS

Reciprocal associations between number of cigarettes smoked and ND criteria were both significant. Cigarette consumption had stronger associations with later ND [β = 0.25, 95% confidence interval (CI) = 0.17-0.32] than dependence had with later cigarette consumption (β = 0.09, 95% CI = 0.01-0.16). Alcohol and cigarette consumption influenced each other; AD scores were associated with later ND scores but not the reverse. Reports of pleasant initial experiences from smoking were associated positively with cigarette consumption and ND the first year after smoking onset; later smoking onset was negatively associated with cigarette consumption the seventh year after onset; parental ND predicted cigarette consumption and ND throughout.

CONCLUSIONS

In adolescent smokers, higher cigarette consumption predicts later severity of DSM-IV nicotine dependence more than the reverse. Smoking and drinking also influence each other mutually over time.

Finding genomic function for genetic associations in nicotine addiction research: the ENCODE project's role in future pharmacogenomic analysis

Tobacco-related behaviors and the underlying addiction to nicotine are complex tangles of genetic and environmental factors. Efforts to understand the genetic component of these traits have identified sites in the genome (single nucleotide polymorphisms, or SNPs) that might account for some part of the role of genetics in nicotine addiction. Encouragingly, some of these candidate SNPs remain significant in meta-analyses. However, genetic associations cannot be fully assessed, regardless of statistical significance, without an understanding of the functional consequences of the alleles present at these SNPs. The proper experimental test for allelic function can be very difficult to define, representing a roadblock in translating genetic results into treatment to prevent smoking and other nicotine-related behaviors. This roadblock can be navigated in part with a new web-based tool, the Encyclopedia of DNA Elements (ENCODE). ENCODE is a compilation of searchable data on several types of biochemical functions or "marks" across the genome. These data can be queried for the co-localization of a candidate SNP and a biochemical mark. The presence of a SNP within a marked region of DNA enables the generation of better-informed hypotheses to test possible functional roles of alleles at a candidate SNP. Two examples of such co-localizations are presented. One example reveals ENCODE's ability to relate a candidate SNP's function with a gene very far from the physical location of the SNP. The second example reveals a new potential function of the SNP, rs4105144, that has been genetically associated with the number of cigarettes smoked per day. Details for accessing the ENCODE data for this SNP are provided to serve as a tutorial. By serving as a bridge between genetic associations and biochemical function, ENCODE has the power to propel progress in untangling the genetic aspects of nicotine addiction - a major public health concern.

Cohort Profile: The Nicotine Dependence in Teens (NDIT) Study

The Nicotine Dependence in Teens (NDIT) study is a prospective cohort investigation of 1294 students recruited in 1999-2000 from all grade 7 classes in a convenience sample of 10 high schools in Montreal, Canada. Its primary objectives were to study the natural course and determinants of cigarette smoking and nicotine dependence in novice smokers. The main source of data was self-report questionnaires administered in class at school every 3 months from grade 7 to grade 11 (1999-2005), for a total of 20 survey cycles during high school education. Questionnaires were also completed after graduation from high school in 2007-08 and 2011-12 (survey cycles 21 and 22, respectively) when participants were aged 20 and 24 years on average, respectively. In addition to its primary objectives, NDIT has embedded studies on obesity, blood pressure, physical activity, team sports, sedentary behaviour, diet, genetics, alcohol use, use of illicit drugs, second-hand smoke, gambling, sleep and mental health. Results to date are described in 58 publications, 20 manuscripts in preparation, 13 MSc and PhD theses and 111 conference presentations. Access to NDIT data is open to university-appointed or affiliated investigators and to masters, doctoral and postdoctoral students, through their primary supervisor (www.nditstudy.ca).

Impact of nicotine metabolism on nicotine's pharmacological effects and behavioral responses: insights from a Cyp2a(4/5)bgs-null mouse

Nicotine metabolism is believed to affect not only nicotine's pharmacological effects but also nicotine addiction. As a key step toward testing this hypothesis, we have studied nicotine metabolism and nicotine's pharmacological and behavioral effects in a novel knockout mouse model [named Cyp2a(4/5)bgs-null] lacking a number of cytochrome P450 genes known to be or possibly involved in nicotine metabolism, including two Cyp2a and all Cyp2b genes. We found that, compared with wild-type mice, the Cyp2a(4/5)bgs-null mice showed >90% decreases in hepatic microsomal nicotine oxidase activity in vitro, and in rates of systemic nicotine clearance in vivo. Further comparisons of nicotine metabolism between Cyp2a(4/5)bgs-null and Cyp2a5-null mice revealed significant roles of both CYP2A5 and CYP2B enzymes in nicotine clearance. Compared with the behavioral responses in wild-type mice, the decreases in nicotine metabolism in the Cyp2a(4/5)bgs-null mice led to prolonged nicotine-induced acute pharmacological effects, in that null mice showed enhanced nicotine hypothermia and antinociception. Furthermore, we found that the Cyp2a(4/5)bgs-null mice developed a preference for nicotine in a conditioned place preference test, a commonly used test of nicotine's rewarding effects, at a nicotine dose that was 4-fold lower than what was required by wild-type mice. Thus, CYP2A/2B-catalyzed nicotine clearance affects nicotine's behavioral response as well as its acute pharmacological effects in mice. This result provides direct experimental support of the findings of pharmacogenetic studies that suggest linkage between rates of nicotine metabolism and smoking behavior in humans.

Predictors of nicotine dependence symptoms among never-smoking adolescents: a longitudinal analysis from the Nicotine Dependence in Teens Study

BACKGROUND

Recent cross-sectional studies suggest some adolescents who have never smoked cigarettes experience nicotine dependence (ND) symptoms and that exposure to second-hand smoke, social exposure to smoking, and alcohol use are plausible correlates. The aim of this study was to replicate and extend these findings by investigating possible predictors of ND symptoms longitudinally.

METHOD

Participants included 847 secondary school students who had never smoked cigarettes enrolled in the Nicotine Dependence in Teens Study. Adolescents completed self-report questionnaires measuring smoking status, ND symptoms, and risk factors for ND in smokers (i.e., socio-demographic indicators, social exposure to smoking, psychosocial indicators, and substance use) in 20 survey cycles from 7 to 11th grade. Generalized estimating equations, which account for repeated measures within individuals, were used to test the predictors of ND symptoms.

RESULTS

Consistent with previous research, 7.8% of never-smokers across all cycles endorsed at least one ND symptom. Younger age (p ≤ .001), country of birth (p ≤ .05), peer smoking (p ≤ .001), teacher smoking (p ≤ .05), depression (p ≤ .05), stress (p ≤ .001), lower self-esteem (p ≤ .05), impulsivity (p ≤ .05), and alcohol use (p ≤ .001) predicted greater ND symptoms in multivariable modeling.

CONCLUSIONS

Replicating previous cross-sectional findings, peer smoking and alcohol use predicted ND symptoms among never-smoking adolescents. Extending these findings, previous predictors only observed among ever-smokers, including socio-demographic and psychosocial indicators, also predicted ND symptoms. This longitudinal investigation demonstrated the temporal relation of the predictors preceding ND symptoms. Future research should consider longer prospective studies with younger children to capture early onset of ND symptoms and with longer follow-up to detect eventual smoking uptake.

Mental disorders and cigarette use among adults in the United States

BACKGROUND

The goal of this study was to determine the association between mental disorders and cigarette consumption and nicotine dependence.

METHODS

Data were drawn from the National Epidemiologic Survey of Alcohol and Related Conditions (NESARC), a nationally representative survey of adults (N = 43,093) aged 18 and older. Relationships between specific anxiety disorders, mood disorders, nondependent cigarette use, nicotine dependence among the whole sample, and nicotine dependence among cigarette users were examined.

RESULTS

After adjusting for demographics and comorbid mental disorders, generalized anxiety disorder (OR = 1.16 (1.29-1.51)), specific phobia (OR = 1.35 (1.21-1.51)), panic disorder (PD) (OR = 1.90 (1.62-2.23)), major depression (MDD) (OR = 1.31 (1.16-1.48)), and bipolar disorder (OR = 1.30 (1.09-1.54)) were associated with increased likelihood of nondependent cigarette use. Specific phobia (OR = 1.69 (1.49-1.91)), PD (OR = 1.82 (1.50-2.21)), MDD (OR = 1.59 (1.38-1.84)), and bipolar disorder (OR = 1.71 (1.39-2.09)) were associated with increased odds of nicotine dependence among the whole sample; social phobia (OR = 1.69 (1.19-2.40)), specific phobia (OR = 1.69 (1.43-2.01)), MDD (OR = 1.65 (1.34-2.02)), and bipolar disorder (OR = 2.38 (1.74-3.24)) were associated with increased risk of nicotine dependence among cigarette users.

CONCLUSIONS

Specific anxiety disorders and mood disorders were uniquely associated with nondependent cigarette use, nicotine dependence among the whole sample, and the risk of nicotine dependence among cigarette users in the United States. Findings suggest that demographic differences, comorbid mood, anxiety, substance, and personality disorders all contributed to previously observed associations between mental disorders and nicotine dependence, explaining these links in some but not all cases.

Translation, cross-cultural adaptation, and reproducibility of the Brazilian portuguese-language version of the Wisconsin Smoking Withdrawal Scale

OBJECTIVE

To cross-culturally adapt the Wisconsin Smoking Withdrawal Scale (WSWS) for use in Brazil and evaluate the reproducibility of the new (Brazilian Portuguese-language) version.

METHODS

The original English version of the WSWS was translated into Brazilian Portuguese. For cross-cultural adaptation, the Brazilian Portuguese-language version of the WSWS was administered to eight volunteers, all of whom were smokers. After adjustments had been made, the WSWS version was back-translated into English. The Brazilian Portuguese-language version was thereby found to be accurate. The final Brazilian Portuguese-language version of the WSWS was applied to 75 smokers at three distinct times. For the assessment of interobserver reproducibility, it was applied twice within a 30-min interval by two different interviewers. For the assessment of intraobserver reproducibility, it was applied again 15 days later by one of the interviewers. Intraclass correlation coefficients (ICCs) were used in order to test the concordance of the answers. The significance level was set at p < 0.05.

RESULTS

Of the 75 volunteers, 43 (57.3%) were female. The overall mean age was 46.3 years. Interobserver and intraobserver reproducibility was determined for each of the WSWS seven domains, the ICCs for which ranged from 0.87 to 0.94 and from 0.76 to 0.92, respectively. The mean time to completion of the WSWS was 6 min and 44 s, and the response time per question ranged from 4.2 to 12.6 s.

CONCLUSIONS

The Brazilian Portuguese-language version of the WSWS is reproducible, fast, and simple. It can therefore be used as a tool for assessing the severity of the symptoms of nicotine withdrawal syndrome.

Predicting nicotine dependence profiles among adolescent smokers: the roles of personal and social-environmental factors in a longitudinal framework

BACKGROUND

Although several studies have reported that symptoms of nicotine dependence can occur after limited exposure to smoking, the majority of research on nicotine dependence has focused on adult smokers. Insufficient knowledge exists regarding the epidemiology and aetiology of nicotine dependence among adolescent smokers. The objective of the present study is to identify the effects of theoretically driven social and individual predictors of nicotine dependence symptom profiles in a population-based sample of adolescent smokers.

METHOD

A longitudinal study among 6,783 adolescents (12 to 14 years old at baseline) was conducted. In the first and second year of secondary education, personality traits and exposure to smoking in the social environment were assessed. Two and a half years later, adolescents' smoking status and nicotine dependence symptom profiles were assessed. A total of 796 adolescents were identified as smokers and included in the analyses.

RESULTS

At follow-up, four distinct dependence symptom profiles were identified: low cravings only, high cravings and withdrawal, high cravings and behavioural dependence, and overall highly dependent. Personality traits of neuroticism and extraversion did not independently predict nicotine dependence profiles, whereas exposure to smoking in the social environment posed a risk for the initial development of nicotine dependence symptoms. However, in combination with environmental exposure to smoking, extraversion and neuroticism increased the risk of developing more severe dependence symptom profiles.

CONCLUSIONS

Nicotine dependence profiles are predicted by interactions between personal and environmental factors. These insights offer important directions for tailoring interventions to prevent the onset and escalation of nicotine dependence. Opportunities for intervention programs that target individuals with a high risk of developing more severe dependence symptom profiles are discussed.

Risk and protective factors for nicotine dependence in adolescence

BACKGROUND

We investigated the role of psychosocial and proximal contextual factors on nicotine dependence in adolescence.

METHODS

Data on a multiethnic cohort of 6th to 10th graders from the Chicago public schools were obtained from four household interviews conducted with adolescents over two years and one interview with mothers. Structural equation models were estimated on 660 youths who had smoked cigarettes by the first interview.

RESULTS

Pleasant initial sensitivity to tobacco use, parental nicotine dependence (ND), adolescent ND and extensiveness of smoking at the initial interview had the strongest total effects on adolescent ND two years later. Perceived peer smoking and adolescent conduct problems were of lesser importance. Parental ND directly impacted adolescent ND two years later and had indirect effects through pleasant initial sensitivity and initial extensiveness of smoking. Parental depression affected initial adolescent dependence and depression but adolescent depression had no effect on ND. The model had greater explanatory power for males than females due partly to the stronger effect of conduct problems on dependence for males than females.

CONCLUSIONS

The findings underscore the importance of the initial drug experience and familial factors on adolescent nicotine dependence and highlight the factors to be the focus of efforts targeted toward preventing ND among adolescents.

Black and White adults' perspectives on the genetics of nicotine addiction susceptibility

AIMS

Emerging research may soon lead to improved quit rates via genetically-tailored smoking cessation treatment. The purpose of this study was to explore individuals' beliefs and attitudes about genetic testing in this context, and how these may differ across racial groups.

DESIGN

Two site qualitative study.

METHODS

Eleven focus groups were conducted in 2007 with 51 Black and 55 White adult participants in Montgomery, AL and Baltimore, MD.

MEASUREMENTS

Questions were asked about smoking as an addiction, the role of genetics in nicotine addiction susceptibility, and undergoing genetic testing to receive tailored smoking cessation treatment. Data were analyzed using content analysis.

FINDINGS

Most participants believed that smoking was an addiction yet were unwilling to endorse the notion that genetics played a role in nicotine addiction susceptibility. However, 91% of White participants and 62% of Black participants indicated that they would likely take a genetic test that would match them to their optimal smoking cessation treatment. The primary potential benefit was a vague sense that additional knowledge about oneself would be of value. Primary barriers included disinterest and skepticism about the test, unwillingness to believe that genetics played a role in nicotine addiction or treatment response, and concerns about psychological consequences.

CONCLUSIONS

The majority of participants, particularly Black participants, did not believe that genetics played a significant role in nicotine addiction susceptibility but were willing to undergo genetic testing. Participants identified some benefit to tailoring smoking treatment by genotype. However, participants also expressed skepticism about the test and concerns about its consequences; these issues would need to be addressed in the clinical encounter.

Comorbid psychiatric disorders and nicotine dependence in adolescence

AIMS

To examine bidirectional influences of onset of psychiatric disorders and nicotine dependence among adolescent smokers.

DESIGN

A prospective longitudinal cohort of adolescents and mothers drawn from a large city school system. Adolescents were interviewed five times and mothers three times over 2 years.

SETTING

Chicago, Illinois.

PARTICIPANTS

Subsample of adolescent smokers (n = 814).

MEASUREMENTS

Selected DSM-IV psychiatric disorders, nicotine dependence and selected risk factors were ascertained.

FINDINGS

Among lifetime smokers, 53.7% experienced at least one nicotine dependence criterion; 26.1% full dependence; 14.1% experienced an anxiety disorder, 18.8% a mood disorder and 29.5% a disruptive disorder. Nicotine dependence and psychiatric disorders were comorbid: nicotine-dependent youths had higher rates of individual and multiple disorders than those not dependent. Controlling for other covariates, mood disorder and nicotine dependence did not predict each other; anxiety disorder predicted nicotine dependence. Bidirectional influences were observed for disruptive disorder and nicotine dependence. Predictors of onset of full nicotine dependence included earlier onset age of tobacco use, high initial pleasant sensitivity to tobacco, alcohol and illicit drug use, abuse and dependence and parental nicotine dependence. Predictors of psychiatric disorder onset included gender, race/ethnicity, other psychiatric disorders, illicit drug abuse or dependence and parental depression and delinquency.

CONCLUSIONS

Initial pleasant experiences of smoking are predictive of later development of nicotine dependence. There may be reciprocal influences between disruptive disorder and development of nicotine dependence in adolescence, and intergenerational transmission of parental nicotine dependence and psychopathology.

Self-efficacy mediates the effect of depression on smoking susceptibility in adolescents

INTRODUCTION

Research indicates that negative affect and/or depression is associated with increased prevalence for smoking and higher levels of nicotine dependence in adults and adolescents. A previous study with adult smokers attempting to quit indicated that low levels of self-efficacy partially mediated depression's adverse effect on posttreatment cessation.

METHOD

The current study attempted to test self-efficacy as a potential mediator between depressive symptoms and smoking susceptibility in adolescents. One thousand and ninety-three nonsmoking high-school students who were part of a large clinical trial evaluating an interactive CD-ROM-based smoking prevention/cessation curriculum (project ASPIRE) were included in this analysis. These students completed an extensive battery before treatment and 18 months after treatment, which included measures of depression, self-efficacy, smoking status, and smoking susceptibility.

RESULTS

Results indicated that self-efficacy partially mediated the positive relationship between baseline depressive symptoms and susceptibility to smoke at 18 months, accounting for approximately 27% of the variance.

CONCLUSIONS

Perhaps future interventions to prevent smoking in adolescents can target self-efficacy potentially resulting in more effective outcomes, particularly in adolescents with current depressive symptoms or who may be at risk for future depression.

Nicotine reduction revisited: science and future directions

Regulation of nicotine levels in cigarettes and other tobacco products is now possible with the passage of the Family Smoking Prevention and Tobacco Control Act (FSPTCA) in 2009, giving the US Food and Drug Administration (FDA) authority to regulate tobacco products, and with Articles 9-11 of the WHO Framework Convention on Tobacco Control. Both regulatory approaches allow establishing product standards for tobacco constituents, including nicotine. The FSPTCA does not allow nicotine levels to be decreased to zero, although the FDA has the authority to reduce nicotine yields to very low, presumably non-addicting levels. The proposal to reduce levels of nicotine to a level that is non-addicting was originally suggested in 1994. Reduction of nicotine in tobacco products could potentially have a profound impact on reducing tobacco-related morbidity and mortality. To examine this issue, two meetings were convened in the US with non-tobacco-industry scientists of varied disciplines, tobacco control policymakers and representatives of government agencies. This article provides an overview of the current science in the area of reduced nicotine content cigarettes and key conclusions and recommendations for research and policy that emerged from the deliberations of the meeting members.

Negative affectivity in smokers applying to smoking cessation clinics: a case-control study

OBJECTIVE

The objective of this study was to assess whether subjects applying to smoking cessation clinics display a higher level of affective symptoms than smokers recruited from the general population.

METHODS

The study was conducted according to a cross-sectional, case-control design. Cases were smokers applying to public smoking cessation clinics for the first time and controls were smokers recruited from the general population. Socio-demographic data and clinical information were collected. Self- (Hospital Anxiety Depression Scale, Beck Depression Inventory, State-Trait Anxiety Inventory) and hetero-administered (Montgomery Asberg Depression Rating Scale, Hamilton Anxiety scale) rating scales were used to assess anxious and depressive symptoms. Nicotine dependence was measured via a self-administered questionnaire (Fagerström Tolerance Questionnaire).

RESULTS

Sixty-eight cases were recruited, individually matched, and compared to controls. Overall, cases had significantly higher scores than controls when the rating scales assessing anxious and depressive symptoms were evaluated.

CONCLUSIONS

Smokers applying to smoking cessation clinics for the first time have a higher level of negative affectivity than smokers from the general population. An evaluation of the level of negative affectivity could be introduced into clinical practice to have a complete assessment of the patient. We propose adding psychological or pharmacological support to complement the smoking cessation program.

Determinants of first puff and daily cigarette smoking in adolescents

Few prospective studies of smoking initiation have investigated a wide range of time-varying and invariant predictor variables at the individual and contextual levels concurrently. In this study (1999-2005), 877 Canadian students (mean age = 12.7 years) who had never smoked at baseline completed self-report questionnaires on cigarette smoking and 32 predictor variables in 20 survey cycles during secondary school. Height and weight were measured in survey cycles 1, 12, and 19. School administrators completed questionnaires on school tobacco control policies/activities, and trained observers collected data on access to tobacco products in commercial establishments near schools. Younger age, single-parent family status, smoking by parents, siblings, friends, and school staff, stress, impulsivity, lower self-esteem, feeling a need to smoke, not doing well at school, susceptibility to tobacco advertising, alcohol use, use of other tobacco products, and attending a smoking-tolerant school were independent determinants of smoking initiation. Independent determinants of daily smoking onset among initiators of nondaily smoking included smoking by siblings and friends, feeling a need to smoke, susceptibility to tobacco advertising, use of other tobacco products, and self-perceived mental and physical addiction. Adolescent tobacco control programs should address multiple individual and contextual-level risk factors. Strategies that address nicotine dependence symptoms are also needed for adolescents who have already initiated smoking.

Sequencing of DSM-IV criteria of nicotine dependence

AIMS

To determine whether there is a sequence in which adolescents experience symptoms of nicotine dependence (ND) as per the DSM-IV.

DESIGN

A two-stage design was implemented to select a multi-ethnic target sample of adolescents from a school survey of 6th-10th graders from the Chicago Public Schools. The cohort was interviewed at home five times with structured computerized interviews at 6-month intervals over a 2-year period.

PARTICIPANTS

Subsample of new tobacco users (n = 353) who had started to use tobacco within 12 months prior to wave 1 or between waves 1 and 5. MEASUREMENTS AND STATISTICAL METHODS: Monthly histories of DSM-IV symptoms of ND were obtained. Log-linear quasi-independence models were estimated to identify the fit of different cumulative models of progression among the four most prevalent dependence criteria (tolerance, impaired control, withdrawal, unsuccessful attempts to quit), indexed by specific symptoms, by gender and race/ethnicity.

FINDINGS

Pathways varied slightly across groups. The proportions who could be classified in a progression pathway not by chance ranged from 50.7% to 68.8%. Overall, tolerance and impaired control appeared first and preceded withdrawal; impaired control preceded attempts to quit. For males, tolerance was experienced first, with withdrawal a minor path of entry; for females withdrawal was experienced last, tolerance and impaired control were experienced first. For African Americans, tolerance by itself was experienced first; for other groups an alternative path began with impaired control.

CONCLUSIONS

The prevalence and sequence of criteria of ND fit our understanding of the neuropharmacology of ND. The order among symptoms early in the process of dependence may differ from the severity order of symptoms among those who persist in smoking.

Nicotine dependence pharmacogenetics: role of genetic variation in nicotine-metabolizing enzymes

Nicotine-dependence pharmacogenetics research is an emerging field, and a number of studies have begun to characterize the clinical relevance and predictive power of genetic variation in drug-metabolizing enzymes and drug target genes for response to medication. The present paper focuses on evidence for the role of nicotine-metabolizing enzymes in smoking behavior and response to treatment. Nicotine metabolism is mediated primarily by cytochrome P450 2A6 (CYP2A6). Genetic variation in the CYP2A6 gene has been linked with several smoking behavior phenotypes. Individuals who carry null or reduced activity alleles for CYP2A6 smoke fewer cigarettes per day, are less dependent on nicotine, and may have an easier time quitting smoking. A phenotypic measure of CYP2A6 enzyme activity, defined as the ratio of the nicotine metabolites 3'hydroxycotinine/cotinine, also predicts successful quitting with the transdermal nicotine patch, and counseling alone. Faster metabolizers of nicotine respond more poorly to these treatments; however, they may be excellent candidates for non-nicotine therapies, such as bupropion. Inherited variation in the CYP2B6 enzyme is also associated with response to bupropion treatment and counseling alone for smoking cessation. Inhibition of the CYP2A6 enzyme to slow nicotine metabolism is a promising approach to increase nicotine availability and potentially reduce harm from tobacco smoking.

Comorbidity of psychiatric disorders and nicotine dependence among adolescents: findings from a prospective, longitudinal study

OBJECTIVE

To examine prospectively the comorbidity of DSM-IV psychiatric disorders and nicotine dependence in adolescence.

METHOD

A multiethnic sample (N = 1,039) of adolescents from grades 6 to 10 in the Chicago public schools (mean age 14.1 years) was interviewed at home five times, and mothers were interviewed three times over a 2-year period (2003-2005). Completion rates at each wave were 96% of the initial sample. Selected DSM-IV psychiatric disorders were ascertained from youths and mothers about youths at two annual waves with the NIMH Diagnostic Interview Schedule for Children, Version IV-Y and IV-P; DSM-IV symptoms of nicotine dependence were ascertained from youths at every wave using a measure developed for adolescents.

RESULTS

Psychiatric disorders most often preceded the onset of the first criterion of nicotine dependence. Prospective associations between psychiatric disorders and nicotine dependence were examined through logistic regressions. After controlling for comorbid disorders, it was found that lifetime disruptive disorder significantly predicted the onset of a nicotine dependence criterion (adjusted odds ratio 2.1). Early onset of any psychiatric disorder increased this risk. Other predictors included novelty seeking and extensiveness of smoking. By contrast, nicotine dependence did not predict the onset of a psychiatric disorder; significant predictors included the youths' prior other psychiatric disorders, novelty seeking, and parental depression and antisocial behavior.

CONCLUSIONS

Nicotine dependence does not seem to contribute to the onset of psychiatric disorders, whereas disruptive disorder is an important etiologic factor for nicotine dependence in adolescence.

Developmental trajectories of criteria of nicotine dependence in adolescence

We describe the nature and predictors of developmental trajectories of symptoms of DSM-IV nicotine dependence in adolescence following smoking initiation. Data are from a longitudinal cohort of 324 new smokers from grades 6-10 in the Chicago Public Schools, interviewed 5 times at 6-month intervals. Monthly data on DSM-IV symptoms of nicotine dependence were available for 36 months. Growth mixture modeling was applied to the monthly histories to identify trajectories of DSM-IV criteria of nicotine dependence. A four-class solution best fitted the data: no DSM criterion (47.7%); early onset/chronic course (19.8%); early onset/remission (17.3%); late onset (15.2%). Blunt use prior to cigarette use was associated with the three symptomatic trajectories. Conduct disorder and prior heavy smoking were associated with Class 2 (chronic). Conduct disorder differentiated Class 2 from Class 4 (late onset), while pleasant initial sensitivity to the first tobacco experience was associated with Classes 2 and 3 (remit) and differentiated Class 2 from Class 4. Novelty seeking characterized Class 3. Parental dependence differentiated chronicity (Class 2) from remission (Class 3) among those who developed symptoms early. Being Hispanic reduced membership in Classes 3 and 4, and being male for Class 3. The data highlight the importance of parental nicotine dependence as a risk factor for early and sustained nicotine dependence by the offspring, pleasant initial sensitivity and conduct disorder for early onset of dependence, and blunt use prior to smoking for all trajectories. The factors important for onset of dependence are not necessarily the same as those for sustained course.

On the development of nicotine dependence in adolescence

Little is known about the natural history of drug dependence. This article describes the development and predictors of DSM-IV nicotine dependence in adolescence when tobacco use is initiated. In a two-stage design, a survey was administered to 6th-10th graders in the Chicago Public Schools to select a cohort of adolescents. Household interviews were conducted with adolescents five times and with one parent (predominantly mothers) three times over 2 years. The analytical sample includes 353 youths, who started using tobacco within 12 months preceding Wave 1 or between Waves 1-5. Survival analysis estimated latency to individual DSM-IV nicotine dependence criteria and the full dependence syndrome. Twenty-five percent of youths experienced the syndrome within 23 months of tobacco use onset. Tolerance, impaired control and withdrawal were experienced most frequently. Youths who developed full dependence experienced their first symptom faster after tobacco use onset than those who experienced only one criterion through the end of the observation period. Cox proportional hazards models estimated the importance of time-constant and time-varying sociodemographic, tobacco and other drug use, parental and peer smoking, social psychological and biological risk factors for experiencing the first criterion and the full syndrome. Pleasant initial sensitivity to tobacco and number of cigarettes smoked the prior month predicted both outcomes. Parental dependence predicted the full syndrome. Significant covariates were generally the same across gender and racial/ethnic subgroups. The predictive significance of the initial smoking experience and parental dependence highlight the potential importance of genetic factors in the etiology of nicotine dependence.

The influence of school smoking policies on student tobacco use

OBJECTIVE

To investigate the association between smoking behavior among secondary school students and school smoking policies.

DESIGN

Cross-sectional provincially representative study.

SETTING

Quebec secondary schools.

PARTICIPANTS

Complete data were available for 763 of 1058 students aged 13 years in 50 schools and for 768 of 1160 students aged 16 years in 57 schools. School principals provided data on school smoking policies. Main Exposure School smoking policies. Outcome Measure Student tobacco use.

RESULTS

Of students aged 13 years, 3.8% of boys and 7.1% of girls smoked daily; 21.0% of boys and 25.2% of girls aged 16 years smoked daily. Of schools, 28.0% permitted staff to smoke indoors, 84.1% permitted staff to smoke outdoors on school grounds, and 83.2% permitted students to smoke outdoors on school grounds. Daily smoking was not associated with policies targeting student smoking or those targeting indoor smoking by staff. In multilevel analyses, girls aged 13 years were almost 5 times more likely to be daily smokers if they attended schools at which staff were permitted to smoke outdoors.

CONCLUSIONS

Younger girls may be more susceptible to social influences at school related to tobacco use. School policies banning smoking by teachers and other school personnel within and outside the school should be an important component of comprehensive adolescent smoking prevention programs.

Separate or sequential exposure to nicotine prenatally and in adulthood: Persistent effects on acetylcholine systems in rat brain regions

Nicotine is a developmental neurotoxicant but the proposed "sensitization-homeostasis" model postulates that even in adulthood nicotine permanently reprograms synaptic function. We administered nicotine to rats throughout gestation or in adulthood (postnatal days PN90-107), simulating plasma levels in smokers, with evaluations on PN105, PN110, PN120, PN130 and PN180. We assessed nicotinic acetylcholine receptor (nAChR) binding, choline acetyltransferase activity, a marker for acetylcholine (ACh) terminals, and hemicholinium-3 (HC3) binding to the choline transporter, an index of ACh presynaptic activity. Prenatal nicotine exposure elicited persistent deficits in HC3 binding in male cerebral cortex and female striatum, but little change in other parameters. Nicotine given in adulthood produced profound nAChR upregulation lasting 2 weeks after discontinuing treatment. Decrements in cerebrocortical and striatal HC3 binding emerged during withdrawal and persisted through PN180, indicative of reduced ACh synaptic activity. Prenatal nicotine did not evoke any major alterations in the response to nicotine given in adulthood. The effects seen here are substantially different from those found previously for nicotine given to adolescent rats, which showed more prolonged nAChR upregulation and profound, widespread and persistent deficits in markers of ACh synaptic function; for adolescents, prenatal nicotine exposure desensitized nAChR responses, exacerbated withdrawal-induced ACh functional deficits, and worsened the long-term outcome. Our results indicate that the effects of nicotine during prenatal or adolescent stages are indeed distinct from the effects in adults, but that even adults show persistent changes after nicotine exposure, commensurate with the sensitization-homeostasis model. These effects may contribute to lifelong vulnerability to readdiction.

Exposure to smoking in popular contemporary movies and youth smoking in Germany

BACKGROUND

Studies have linked exposure to movie smoking and smoking initiation among adolescents in the United States, but there has been only one published study of adolescents outside the U.S.

METHOD

A cross-sectional survey of 5586 schoolchildren aged 10-17 with a mean of 12.8 (SD=1.2) years from randomly selected secondary schools in Schleswig-Holstein, Germany, was taken in October/November 2005. In August 2006, using previously validated methods, exposure to movie smoking was estimated from 398 internationally distributed films (98% produced and distributed by U.S. studios) released in Germany and examined its relationship with ever and current (30-day) smoking.

RESULTS

Overall, 40.7% of the sample had tried smoking, and 12.3% were current smokers. The sample quartile (Q) of movie smoking exposure was significantly associated with the prevalence of smoking initiation: 0.17 of adolescents in Q1 had tried smoking; 0.35 in Q2; 0.47 in Q3; and 0.64 in Q4. Movie smoking exposure was significantly associated with the prevalence of current smoking: 0.03 for adolescents in Q1; 0.08 in Q2; 0.14 in Q3; and 0.25 in Q4. After controlling for sociodemographics, parent/friend/sibling smoking, school performance, personality characteristics, TV consumption, receptivity to tobacco marketing, and parenting style, the adjusted odds ratios for having tried smoking were 1.7 (95% confidence interval [CI]=1.4-2.1) for Q2, 1.8 (95% CI=1.5-2.3) for Q3, and 2.2 (95% CI=1.8-2.8) for Q4 compared with adolescents in Q1. The adjusted odds ratios for current smoking were 1.4 (95% CI=0.9-2.2) for Q2, 1.7 (95% CI=1.1-2.6) for Q3, and 2.0 (95% CI=1.3-3.1) for Q4 compared with adolescents in Q1.

CONCLUSIONS

Smoking in internationally distributed movies is associated with ever and current smoking among German adolescents. This suggests the need for prospective studies of this association in countries other than the U.S. and research into the potential impact of countrywide policies that would limit exposure of young adolescents to movie smoking.

The role of CYP2A6 in the emergence of nicotine dependence in adolescents

OBJECTIVES

The objectives of our study were to evaluate whether genetic variation in nicotine metabolic inactivation accounted for the emergence of nicotine dependence from mid- to late adolescence and whether initial smoking experiences mediated this effect.

METHODS

Participants were 222 adolescents of European ancestry who participated in a longitudinal cohort study of the biobehavioral determinants of adolescent smoking. Survey data were collected annually from grade 9 to the end of grade 12. Self-report measures included nicotine dependence, smoking, age first smoked, initial smoking experiences, peer and household member smoking, and alcohol and marijuana use. DNA collected via buccal swabs was assessed for CYP2A6 alleles that are common in white people and are demonstrated to decrease enzymatic function (CYP2A6*2, *4, *9, *12).

RESULTS

Latent growth-curve modeling indicated that normal metabolizers (individuals with no detected CYP2A6 variants) progressed in nicotine dependence at a faster rate and that these increases in nicotine dependence leveled off more slowly compared with slower metabolizers (individuals with CYP2A6 variants). Initial smoking experiences did not account for how CYP2A6 genetic variation impacts nicotine dependence.

CONCLUSIONS

These findings may help to promote a better understanding of the biology of smoking behavior and the emergence of nicotine dependence in adolescents and inform future work aimed at understanding the complex interplay between genetic, social, and psychological factors in adolescent smoking behavior.