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

Nicotine dependence and sleep quality in young adults

INTRODUCTION

More cigarette smokers report poor sleep quality than non-smokers, but the association between nicotine dependence (ND) and sleep quality has not been well-characterized. The objective of this study was to describe the associations among frequency and intensity of cigarette smoking, ND symptoms, and sleep quality in young adults.

METHODS

Data on past-year smoking frequency, number of cigarettes smoked in the past month, five ND indicators (i.e., withdrawal, craving, self-medication symptoms, mFTQ, ICD-10 criteria for tobacco dependence), and sleep quality (measured with the Pittsburgh Sleep Quality Index (PSQI)) were collected in 2011-12 in self-report questionnaires completed by 405 young adult smokers (mean age 24 (0.6) years; 45% male; 45% daily smokers) participating in a longitudinal investigation of the natural course of ND. Associations between indicators of cigarette smoking, ND symptoms, and sleep quality were examined in multivariable logistic regression analyses controlling for age, sex, mother's education, and alcohol use.

RESULTS

Thirty-six percent of participants reported poor sleep quality (PSQI>5). Higher cigarette consumption (OR(95% CI), 1.03(1.001-1.05)) but not frequency of past-year smoking, more frequent withdrawal symptoms (1.05(1.004-1.10)), more frequent cravings (1.05(1.004-1.10)), higher mFTQ scores (1.14(1.02-1.27)), and endorsing more ICD-10 criteria for tobacco dependence (1.19(1.04-1.36)) were also associated with poor sleep quality.

CONCLUSION

Cigarette smoking and ND symptoms are associated with poor sleep quality in young adult smokers. Advice from practitioners to cut back on number of cigarettes smoked per day and treatment of ND symptoms may improve sleep quality in young adult smokers.

Self-esteem moderates the associations between body-related self-conscious emotions and depressive symptoms

The objectives of this study were to describe the cross-sectional associations between body-related self-conscious emotions and depressive symptoms in young adults and examine self-esteem as a moderator of these associations. Data from a population-based sample of 811 young adults were analyzed using hierarchical multivariate linear regression analysis. Body-related shame ( β = .26) and guilt ( β = .25) were positively related to frequency of depressive symptoms. Self-esteem was negatively related to frequency of depressive symptoms ( β = −.46). Self-esteem moderated the association between body-related guilt and frequency of depressive symptoms. These findings suggest promoting self-esteem may help to reduce the negative effects of body-related guilt on depressive symptoms.

Relationships Between Current and Past Binge Drinking and Systolic Blood Pressure in Young Adults

PURPOSE

Heavy episodic (i.e., "binge") drinking (i.e., ≥five drinks/occasion) is highly prevalent among young adults; those who binge do so four times per month on average, consuming nine drinks on average on each occasion. Although it is well established that chronic heavy drinking (≥two alcoholic beverages per day) increases the risk of hypertension, the relationship between binge drinking and blood pressure is not well described. Our aim was to describe the relationship between frequency of binge drinking, both current (at age 24 years) and past (at age 20 years), and systolic blood pressure (SBP) at age 24 years.

METHODS

Participants (n = 756) from the longitudinal Nicotine Dependence in Teens study reported alcohol consumption at ages 20 and 24 years and had SBP measured at age 24 years. We examined the association between binge drinking and SBP using multiple linear regression, controlling for sex, race/ethnicity, education, monthly drinking in high school, cigarette smoking, and body mass index.

RESULTS

Compared to nonbinge drinkers, SBP at age 24 years was 2.61 [.41, 4.82] mm Hg higher among current monthly bingers and 4.03 [1.35, 6.70] mm Hg higher among current weekly bingers. SBP at age 24 years was 2.90 [.54, 5.25] mm Hg higher among monthly bingers at age 20 years and 3.64 [.93, 6.35] mm Hg higher among weekly bingers at age 20 years, compared to nonbinge drinkers.

CONCLUSIONS

Frequent binge drinking at ages 20 and 24 years is associated with higher SBP at age 24 years and may be implicated in the development of hypertension.

Variation in CYP2A6 and tobacco dependence throughout adolescence and in young adult smokers

BACKGROUND

Smoking is influenced by genetic factors including variation in CYP2A6 and CYP2B6, which encode nicotine-metabolizing enzymes. In early adolescence, CYP2A6 slow nicotine metabolism was associated with higher dependence acquisition, but reduced cigarette consumption. Here we extend this work by examining associations of CYP2A6 and CYP2B6 with tobacco dependence acquisition in a larger sample of smokers followed throughout adolescence.

METHODS

White participants from the Nicotine Dependence in Teens cohort that had ever inhaled (n=421) were followed frequently from age 12-18 years. Cox's proportional hazards models compared the risk of ICD-10 tobacco dependence acquisition (score 3+) for CYP2A6 and CYP2B6 metabolism groups. Early smoking experiences, as well as amount smoked at end of follow-up, was also computed. At age 24 (N=162), we assessed concordance between self-reported cigarette consumption and salivary cotinine.

RESULTS

In those who initiated inhalation during follow-up, CYP2A6 slow (vs. normal) metabolizers were at greater risk of dependence (hazards ratio (HR)=2.3; 95% CI=1.1, 4.8); CYP2B6 slow (vs. normal) metabolizers had non-significantly greater risk (HR=1.5; 95% CI=0.8, 2.6). Variation in CYP2A6 or CYP2B6 was not significantly associated with early smoking symptoms or cigarette consumption at end of follow-up. At age 24, neither gene was significantly associated with dependence status. Self-reported consumption was associated with salivary cotinine, a biomarker of tobacco exposure, acquired at age 24 (B=0.37; P<0.001).

CONCLUSIONS

Our findings extend previous work indicating that slow nicotine metabolism mediated by CYP2A6, and perhaps CYP2B6, increases risk for tobacco dependence throughout adolescence.

Confirmatory factor analysis of the Autonomy over Tobacco Scale (AUTOS) in adults

INTRODUCTION

The Autonomy over Tobacco Scale (AUTOS), a 12-item self-administered questionnaire, was designed to measure autonomy in three correlated lower-order symptom domains: withdrawal, psychological dependence, and cue-induced craving. The factor structure of the AUTOS remains an open question; confirmatory analyses in adolescents supported the hierarchical structure, while exploratory analyses in adolescents and adults yield single-factor solutions. Here we seek to determine whether the hypothesized hierarchical structure is valid in adult smokers.

METHODS

The AUTOS was administered to two independent convenience samples of adult current smokers: a calibration sample recruited in the US for online studies, and a confirmation sample drawn from the prospective Nicotine Dependence in Teens study in Montreal. We tested competing hierarchical and single-factor models using the robust weighted least-squares (WLSMV) estimation method.

RESULTS

A single-factor model that allowed correlated error variances between theoretically related items fit well in the calibration sample (n = 434), χ(2)SB(52) = 165.71; χ(2)/df = 3.19; SRMR = 0.03; CFI = 0.96; NNFI = 0.95; RMSEA = 0.07 (95% CI: 0.06, 0.08). Reliability of the single factor was high (ωB = 0.92) and construct validity was adequate. In the confirmation sample (n = 335), a similar model fit well:χ(2)SB(53) = 126.94; χ(2)/df = 2.44; SRMR = 0.04; CFI = 0.95; NNFI = 0.93; RMSEA = 0.07 (95% CI: 0.05, 0.08). Reliability of the single factor was again high (ωB = 0.92) and construct validity was adequate.

CONCLUSION

The AUTOS is unidimensional in adult smokers.

Number of years of participation in some, but not all, types of physical activity during adolescence predicts level of physical activity in adulthood: Results from a 13-year study

Background

Adolescent physical activity (PA) levels track into adulthood. However it is not known if type of PA participated in during adolescence is associated with PA levels later in life. We aimed to identify natural groupings of types of PA and to assess whether number of years participating in these different groupings during adolescence is related to PA level in early adulthood.

Methods

673 adolescents in Montreal, Canada, age 12–13 years at baseline (54 % female), reported participation in 29 physical activities every 3 months over 5 years (1999–2005). They also reported their PA level at age 24 years (2011–12). PA groupings among the 29 physical activities were identified using factor analysis. The association between number of years participating in each grouping during adolescence and PA level at age 24 was estimated using linear regression within a general estimating equation framework.

Results

Three PA groupings were identified: “sports”, “fitness and dance”, and “running”. There was a positive linear relationship between number of years participating in sports and running in adolescence and PA level at age 24 years (β (95 % confidence interval) = 0.09 (0.04-0.15); 0.08 (0.01-0.15), respectively). There was no relationship between fitness and dance in adolescence and PA level at age 24.

Conclusions

The association between PA participation in adolescence and PA levels in young adulthood may be specific to certain PA types and to consistency of participation during adolescence. Results suggest that efforts to establish the habit of participation in sports and running in adolescence may promote higher PA levels in adulthood.

Recurrent suicidal ideation in young adults

OBJECTIVES

Recurrent suicidal ideation (SI) may be linked to an increased risk of making suicide plans and suicide attempts. The objectives were to describe the frequency of SI recurrence in a population-based sample of young adults, and to compare mental health diagnoses, substance use, use of health services and medication use among those with and without recurrent SI.

METHODS

Data were collected from 785 participants at age 20 years and again at age 24. Chi-square tests were used to compare participants with and without recurrent SI.

RESULTS

Of 56 participants who reported SI at age 20, 32% reported SI four years later. Thirty-nine percent of participants with recurrent SI reported poor mental health compared to 8% of participants who never reported SI; 11% (vs. 4%) had sought professional help, 44% (vs. 8%) had been diagnosed with a mood and/or anxiety disorder, and 22% (vs. 2%) had taken medication for a mental health problem. Past-year substance use was higher among those with recurrent SI than among those with no SI: 67% vs. 42% smoked cigarettes, 56% vs. 39% used other tobacco products, 89% vs. 74% binge drank, 56% vs. 42% used marijuana and 33% vs. 17% reported using illicit drugs.

CONCLUSION

One third of young adults with a history of SI reported SI four years later. Because SI can recur, clinicians should monitor young adults with a history of SI, assess their substance use and mood/anxiety disorders and if needed, refer them for psychological or psychiatric care.

Genetic variants and early cigarette smoking and nicotine dependence phenotypes in adolescents

Background

While the heritability of cigarette smoking and nicotine dependence (ND) is well-documented, the contribution of specific genetic variants to specific phenotypes has not been closely examined. The objectives of this study were to test the associations between 321 tagging single-nucleotide polymorphisms (SNPs) that capture common genetic variation in 24 genes, and early smoking and ND phenotypes in novice adolescent smokers, and to assess if genetic predictors differ across these phenotypes.

Methods

In a prospective study of 1294 adolescents aged 12–13 years recruited from ten Montreal-area secondary schools, 544 participants who had smoked at least once during the 7–8 year follow-up provided DNA. 321 single-nucleotide polymorphisms (SNPs) in 24 candidate genes were tested for an association with number of cigarettes smoked in the past 3 months, and with five ND phenotypes (a modified version of the Fagerstrom Tolerance Questionnaire, the ICD-10 and three clusters of ND symptoms representing withdrawal symptoms, use of nicotine for self-medication, and a general ND/craving symptom indicator).

Results

The pattern of SNP-gene associations differed across phenotypes. Sixteen SNPs in seven genes (ANKK1, CHRNA7, DDC, DRD2, COMT, OPRM1, SLC6A3 (also known as DAT1)) were associated with at least one phenotype with a p-value <0.01 using linear mixed models. After permutation and FDR adjustment, none of the associations remained statistically significant, although the p-values for the association between rs557748 in OPRM1 and the ND/craving and self-medication phenotypes were both 0.076.

Conclusions

Because the genetic predictors differ, specific cigarette smoking and ND phenotypes should be distinguished in genetic studies in adolescents. Fifteen of the 16 top-ranked SNPs identified in this study were from loci involved in dopaminergic pathways (ANKK1/DRD2, DDC, COMT, OPRM1, and SLC6A3).

Impact

Dopaminergic pathways may be salient during early smoking and the development of ND.

Recalled first reactions to inhaling nicotine predict the level of physical dependence

BACKGROUND

The level of physical dependence is a measure of addiction that correlates highly with addiction-associated changes in brain structure. We sought to determine whether age at first inhalation and initial reactions to inhaling nicotine are related to level of physical dependence in early adulthood.

METHODS

Young adults (n=312; mean age=24 years; 51% female) from the Nicotine Dependence in Teens study who had smoked at least once in the preceding three months completed self-report questionnaires in 2011-12. We assessed level of physical dependence with three validated self-report items assessing 'wanting,' 'craving' and 'needing' triggered by nicotine deprivation. Survey items assessed smoking behavior, including age at first inhalation, and recalled first reactions to inhaling nicotine.

RESULTS

After adjusting for covariates, experiencing relaxation, heart racing/pounding, rush or "buzz" (OR=1.45; 95% CI: 1.08, 1.94) and dizziness (OR=1.58; 95% CI: 1.15, 2.18) at first nicotine inhalation were associated with an increased odds of being at a higher level of physical dependence in young adulthood; the association for experiencing relaxation (OR=1.78; 95% CI: 1.20, 2.64) and heart racing/pounding (OR=1.51; 95% CI: 1.00, 2.28) persisted after additionally controlling for all other first reactions. Neither age at first inhalation nor unpleasant first reactions predicted level of physical dependence.

CONCLUSIONS

In accordance with prior research, our findings suggest that smokers who are particularly sensitive to the pleasant, "buzz-related" and generally arousing effects of nicotine may be more likely to attain higher levels of physical dependence.