Rubin Khoddam

Association of Electronic Cigarette Use With Initiation of Combustible Tobacco Product Smoking in Early Adolescence

IMPORTANCE Exposure to nicotine in electronic cigarettes (e-cigarettes) is becoming increasingly common among adolescents who report never having smoked combustible tobacco. OBJECTIVE To evaluate whether e-cigarette use among 14-year-old adolescents who have never tried combustible tobacco is associated with risk of initiating use of 3 combustible tobacco products (ie, cigarettes, cigars, and hookah). DESIGN, SETTING, AND PARTICIPANTS Longitudinal repeated assessment of a school-based cohort at baseline (fall 2013, 9th grade, mean age = 14.1 years) and at a 6-month follow-up (spring 2014, 9th grade) and a 12-month follow-up (fall 2014, 10th grade). Ten public high schools in Los Angeles, California, were recruited through convenience sampling. Participants were students who reported never using combustible tobacco at baseline and completed follow-up assessments at 6 or 12 months (N = 2530). At each time point, students completed self-report surveys during in-classroom data collections. EXPOSURE Student self-report of whether he or she ever used e-cigarettes (yes or no) at baseline. MAIN OUTCOMES AND MEASURES Six- and 12-month follow-up reports on use of any of the following tobacco products within the prior 6 months: (1) any combustible tobacco product (yes or no); (2) combustible cigarettes (yes or no), (3) cigars (yes or no); (4) hookah (yes or no); and (5) number of combustible tobacco products (range: 0-3). RESULTS Past 6-month use of any combustible tobacco product was more frequent in baseline e-cigarette ever users (n = 222) than never users (n = 2308) at the 6-month follow-up (30.7% vs 8.1%, respectively; difference between groups in prevalence rates, 22.7% [95% CI, 16.4%-28.9%]) and at the 12-month follow-up (25.2% vs 9.3%, respectively; difference between groups, 15.9% [95% CI, 10.0%-21.8%]). Baseline e-cigarette use was associated with greater likelihood of use of any combustible tobacco product averaged across the 2 follow-up periods in the unadjusted analyses (odds ratio [OR], 4.27 [95% CI, 3.19-5.71]) and in the analyses adjusted for sociodemographic, environmental, and intrapersonal risk factors for smoking (OR, 2.73 [95% CI, 2.00-3.73]). Product-specific analyses showed that baseline e-cigarette use was positively associated with combustible cigarette (OR, 2.65 [95% CI, 1.73-4.05]), cigar (OR, 4.85 [95% CI, 3.38-6.96]), and hookah (OR, 3.25 [95% CI, 2.29-4.62]) use and with the number of different combustible products used (OR, 4.26 [95% CI, 3.16-5.74]) averaged across the 2 follow-up periods. CONCLUSIONS AND RELEVANCE Among high school students in Los Angeles, those who had ever used e-cigarettes at baseline compared with nonusers were more likely to report initiation of combustible tobacco use over the next year. Further research is needed to understand whether this association may be causal.

Impact of adolescent marijuana use on intelligence : Results from two longitudinal twin studies

Significance Marijuana is the most commonly used recreational drug in the United States. Some studies suggest that marijuana use in adolescence is linked to declines in intellectual functioning. Because of the infeasibility of studying this phenomenon experimentally, it is unclear whether the association can be causally attributed to marijuana use itself or is instead the result of confounding factors. We approach this issue quasiexperimentally using longitudinal samples of adolescent twins. Among twin pairs discordant for marijuana use, we assessed intelligence quotient (IQ) score changes while adjusting for the effects of genetic influences and other factors shared by members of the same twin pair. Results suggest that familial confounds underlie the association between adolescent marijuana use and declining IQ scores. Marijuana is one of the most commonly used drugs in the United States, and use during adolescence—when the brain is still developing—has been proposed as a cause of poorer neurocognitive outcome. Nonetheless, research on this topic is scarce and often shows conflicting results, with some studies showing detrimental effects of marijuana use on cognitive functioning and others showing no significant long-term effects. The purpose of the present study was to examine the associations of marijuana use with changes in intellectual performance in two longitudinal studies of adolescent twins (n = 789 and n = 2,277). We used a quasiexperimental approach to adjust for participants’ family background characteristics and genetic propensities, helping us to assess the causal nature of any potential associations. Standardized measures of intelligence were administered at ages 9–12 y, before marijuana involvement, and again at ages 17–20 y. Marijuana use was self-reported at the time of each cognitive assessment as well as during the intervening period. Marijuana users had lower test scores relative to nonusers and showed a significant decline in crystallized intelligence between preadolescence and late adolescence. However, there was no evidence of a dose–response relationship between frequency of use and intelligence quotient (IQ) change. Furthermore, marijuana-using twins failed to show significantly greater IQ decline relative to their abstinent siblings. Evidence from these two samples suggests that observed declines in measured IQ may not be a direct result of marijuana exposure but rather attributable to familial factors that underlie both marijuana initiation and low intellectual attainment.

A prospective study of the Acquired Preparedness Model: the effects of impulsivity and expectancies on smoking initiation in college students.

This study reports on a prospective test of the Acquired Preparedness Model, which posits that impulsivity influences cigarette smoking through the formation of more positive and fewer negative expectancies about smoking effects. College freshman never-smokers (n = 400; 45% male) completed a baseline interview and quarterly online follow-up assessments for 15 months after baseline. Structural equation modeling indicated that the effects of the impulsivity components of sensation seeking and negative urgency on risk of smoking initiation were mediated by expectancies for positive and negative reinforcement from smoking, respectively. Expectancies about negative consequences from smoking predicted initiation but did not mediate the effects of sensation seeking or negative urgency. Findings are consistent with the Acquired Preparedness Model and suggest that heightened impulsivity is associated with heightened expectancies for reinforcement from smoking, and thus with greater risk for smoking initiation.

Examining the stability of young-adult alcohol and tobacco co-use: A latent transition analysis

Although use of both alcohol and tobacco is common among college-attending young adults, little is known about the stability of co-use over time. Difficulties in studying change in these behaviors may reflect inconsistencies in how smoking in particular is categorized. This study used longitudinal data, gathered at three time points three months apart, to examine cigarette and alcohol use profiles and the stability of profile structure and membership. Undergraduate student smokers’ (N = 320) past 30-day alcohol and cigarette use was assessed using the timeline followback procedure. Smoking (number of cigarettes and number of smoking days) and drinking (number of drinks and number of binges) were entered into a latent transition analysis (LTA) to identify the latent taxonomic structure within the sample, and determine the probability of movement between groups over time. A three-profile solution emerged at each time point. The LTA probabilities highlighted both progression and reduction in the lower-use groups. Overall, findings revealed notable changes in tobacco and alcohol use behaviors over the span of six months, affecting both profile structures and individual membership status. This suggests that among young adults both tobacco and alcohol use are temporally unstable behaviors, particularly among those using at lower levels.

Distress Tolerance as a Correlate of Tobacco Dependence and Motivation: Incremental Relations over and above Anxiety and Depressive Symptoms

ABSTRACT Distress tolerance—the capacity to withstand distressing states—is implicated in the etiology of regular smoking. The present study extends past research by examining whether relations between perceived distress tolerance and smoking-related factors: (1) differ across subdimensions of distress tolerance (Tolerance, Appraisal, Regulation, Absorption); (2) extend across measures of dependence, negative reinforcement smoking, and craving; and (3) are incremental to depressive and anxiety symptoms. Results showed that global distress tolerance was associated with measures of dependence, negative reinforcement, and craving even after controlling for affective symptomatology. Subdimensions of distress tolerance were not uniquely related to smoking outcomes in unadjusted or adjusted models. These findings suggest that: (a) distress tolerance is uniquely implicated in smoking over and above affective symptomatology; and (b) specific subdimensions of distress tolerance do not provide more information about smoking-related characteristics than global dimensions; and (c) addressing distress tolerance in smoking cessation interventions may promote successful cessation.

A review of the prevalence and co‐occurrence of addictions in US ethnic/racial groups: Implications for genetic research

BACKGROUND AND OBJECTIVES We conducted a review of the prevalence and co-occurrence of 12 types of addictions in US ethnic/racial groups and discuss the implications of the results for genetic research on addictions. METHODS We utilized MEDLINE and PsycINFO databases to review the literature on alcohol, tobacco, marijuana, illicit drugs, gambling, eating/food, internet, sex, love, exercise, work, and shopping. We present results for each addiction based on total US prevalence, prevalence within ethnic groups, and co-occurrence of addictions among ethnic groups when available. RESULTS This review indicates very little research has examined the interrelationships of addictive behaviors among US ethnic groups. The studies that exist have focused nearly exclusively on comorbidity of substances and gambling behaviors. Overall findings suggest differences among US ethnic groups in prevalence of addictions and in prevalence of addiction among those who use substances or engage in gambling. Almost no ethnic group comparisons of other addictive behaviors including eating/food, internet, love, sex, exercise, work, and shopping were identified in the literature. CONCLUSIONS Despite large-scale research efforts to examine alcohol and substance use disorders in the United States, few studies have been published that examine these addictive behaviors among ethnic groups, and even fewer examine co-occurrence and comorbidity with other addictions. SCIENTIFIC SIGNIFICANCE Even with the limited studies, these findings have implications for genetic research on addictive behaviors. We include a discussion of these implications, including issues of population stratification, disaggregation, admixture, and the interplay between genetic and environmental factors in understanding the etiology and treatment of addictions. (Am J Addict 2017;26:424-436).

Internalizing symptoms and conduct problems: Redundant, incremental, or interactive risk factors for adolescent substance use during the first year of high school?

AIM The complex interplay of externalizing and internalizing problems in substance use risk is not well understood. This study tested whether the relationship of conduct problems and several internalizing disorders with future substance use is redundant, incremental, or interactive in adolescents. METHODS Two semiannual waves of data from the Happiness and Health Study were used, which included 3383 adolescents (M age=14.1years old; 53% females) in Los Angeles who were beginning high school at baseline. Logistic regression models tested the likelihood of past six-month alcohol, tobacco, marijuana, and any substance use at follow-up conditional on baseline conduct problems, symptoms of one of several internalizing disorders (i.e., Social Phobia and Major Depressive, Generalized Anxiety, Panic, and Obsessive-Compulsive Disorder), and their interaction adjusting for baseline use and other covariates. FINDINGS Conduct problems were a robust and consistent risk factor of each substance use outcome at follow-up. When adjusting for the internalizing-conduct comorbidity, depressive symptoms were the only internalizing problem whose risk for alcohol, tobacco, and any substance use was incremental to conduct problems. With the exception of social phobia, antagonistic interactive relationships between each internalizing disorder and conduct problems were found when predicting any substance use; internalizing symptoms was a more robust risk factor for substance use in teens with low (vs. high) conduct problems. CONCLUSIONS Although internalizing and externalizing problems both generally increase risk of substance use, a closer look reveals important nuances in these risk pathways, particularly among teens with comorbid externalizing and internalizing problems.

Social Self-Control Is a Statistically Nonredundant Correlate of Adolescent Substance Use

ABSTRACT The social self-control scale (SSCS), which taps provocative behavior in social situations, was compared with five potentially overlapping measures (i.e., temperament-related impulsivity, psychomotor agitation-related self-control, perceived social competence, and rash action in response to negative and positive affectively charged states) as correlates of tobacco use and other drug use among a sample of 3,356 ninth-grade youth in Southern California high schools. While there was a lot of shared variance among the measures, the SSCS was incrementally associated with both categories of drug use over and above alternate constructs previously implicated in adolescent drug use. Hence, SSC may relate to adolescent drug use through an etiological pathway unique from other risk constructs. Given that youth who tend to alienate others through provocative social behavior are at risk for multiple drug use, prevention programming to modify low SSC may be warranted.

Family history density predicts long term substance use outcomes in an adolescent treatment sample

AIMS This study explored whether the density of family history (FH) of substance use disorders relates to post-treatment substance use outcomes in adolescents, with the primary aim of determining whether FH exerts a relatively stronger influence on longer-term outcomes. METHOD The present investigation examined adolescents (ages 12-18, n=366) from two independent samples who were treated for alcohol/substance use disorder (ASUD) and re-assessed during the eight years following treatment with identical methodology. Primary substance use outcomes were assessed at 1, 2, 4, 6, and 8 years post-treatment and included total drinks, days using marijuana, and days using other drugs. RESULTS In hierarchical linear models there were significant FH density×linear time interactions for total drinks (z=12.75, p<0.001) and marijuana use days (z=4.39, p<0.001); greater FH density predicted more total drinks and more marijuana use days, with both associations becoming stronger over time. The increasing linkage between FH and other drug use was not significant over time. CONCLUSIONS Findings are consistent with previous research indicating that the risk associated with FH increases over time, especially in relation to quantity/frequency measures of alcohol and marijuana use. By extending these findings to an adolescent clinical sample, the current study highlights that FH density of alcohol and drug dependence is a risk factor for poorer long-term outcomes for adolescent-onset ASUD youth as they transition into adulthood. Future work should explore the mechanisms underlying greater post-treatment substance use for adolescents/young adults with greater FH density.

Family smoking history moderates the effect of expectancies on smoking initiation in college students

AIMS This report was designed to test the hypothesis that family history of smoking (FH) would moderate the effects of positive and negative smoking expectancies on initiation in a college sample. DESIGN Secondary analysis of a study of college freshmen never-smokers (n=196; 46% male) who completed a baseline interview and quarterly online follow-up assessments for 15 months. FINDINGS Analyses indicated that FH moderated the effect of negative outcome expectancies (p=.003) but not the effects of expectancies for positive or negative reinforcement on the probability of smoking initiation. Stronger negative expectancies were associated with a decreased risk of initiation for family history positive but not family history negative participants. CONCLUSIONS Findings are consistent with previous tobacco research indicating that FH+adolescents have more negative expectancies about cigarette smoking. This suggests that adolescents observing negative consequences or receiving negative messages from their parents about cigarettes may be less likely to experiment with smoking.