Multi-directional pathways of tobacco and marijuana use, including comorbid use, among a population-based cohort of adolescents in Texas: A six-wave cross-lagged model.

PURPOSE: Past 30-day tobacco and marijuana use commonly occur among adolescents. It is unclear whether use of one product precedes the other, especially given the new climate surrounding marijuana legalization and the increasing popularity of e-cigarettes. METHODS: Six-panel cross-lagged regression models, with six months between each panel/Wave (2014-17), were used to model stability paths, bi-directional paths, and comorbid paths (i.e., correlations) between past 30-day use of marijuana and tobacco products. Data were derived from three cohorts of adolescents (n = 3907; weighted N = 461,069) in 6th, 8th, and 10th grades at baseline. RESULTS: Few bidirectional relationships between past 30-day tobacco and marijuana use were observed in early adolescence (6th grade). During the middle adolescence developmental period (8th grade), past 30-day marijuana use was prospectively associated with greater risk of past 30-day tobacco use. In late adolescence (10th grade), increased odds of past 30-day marijuana use given prior past 30-day e-cigarette use, and vice versa, were observed. For all cohorts, stability paths were common, especially for past 30-day marijuana use. Comorbid use was common in middle adolescence (8th grade) but small in magnitude. CONCLUSIONS: This is the first study to longitudinally situate comorbid, past 30-day use of tobacco and marijuana and simultaneously examine bi-directional past 30-day use of these products for adolescents. Marijuana use more often and more strongly predicted subsequent tobacco use than the reverse, especially during middle adolescence (13-15 years old). Marijuana use should be considered when creating interventions that address adolescent e-cigarette use in the U.S.

Multidirectional Pathways of Tobacco and Marijuana Use, Including Comorbid Use, Among Young Adults (Aged 18-25 Years) in Texas: A Six-Wave Cross-Lagged Model.

PURPOSE: Prevalence of past 30-day tobacco and marijuana use are highest among young adults in the U.S., and comorbid use of these products is common. However, it is unclear whether the use of one product precedes the other-an important consideration, given the new climate surrounding marijuana legalization and the popularity of e-cigarette products. METHODS: Six-panel cross-lagged regression models, with 6 months between each panel/wave, were used to model bidirectional paths between past 30-day use and comorbid use of marijuana and tobacco products from 2014 to 2017 among young adults (N = 5,221 college students, aged 18-25 years). RESULTS: Combustible tobacco use and e-cigarette use were prospectively associated with greater risk of future marijuana use while controlling for the stability of use over time, age, race/ethnicity, and sex. Marijuana use was prospectively associated with greater risk of future combustible tobacco and e-cigarette use. Comorbid use was common, but while the odds of comorbid use decreased with increasing age, odds of tobacco use increased. CONCLUSIONS: More young adults may be consolidating their use than are successfully ceasing their tobacco or marijuana use as they mature through young adulthood. Although we observed decreases in comorbid use of combustible tobacco with marijuana and e-cigarettes with marijuana, we simultaneously observed strong stability in single use of these products over time. Taken together, these results should help structure interventions specific to young adults that target use and comorbid use in early young adulthood to discourage initiation, encourage cessation, and curb subsequent escalation in later young adulthood.

Understanding susceptibility to e-cigarettes: A comprehensive model of risk factors that influence the transition from non-susceptible to susceptible among e-cigarette naïve adolescents.

The primary objective of this study was to identify risk factors associated with becoming susceptible to e-cigarette use over the course of a year among e-cigarette-naive adolescents considering a comprehensive model of risk factors (risk perceptions, social influences and norms, affective risk factors, and other behavioral risk factors). Data came from the Texas Adolescent Tobacco and Marketing Surveillance system (TATAMS), a longitudinal cohort study of students who were in the 6th, 8th, and 10th grades (n = 3907) during the 2014-2015 academic year. Weighted generalized linear mixed models assessed multiple predictors' associated with the transition to susceptibility to e-cigarettes at 12 months. Among 6th graders, family influence, use of other substances, and positive affect were important. Adolescents transitioning from 8th grade to high school presented the greatest number of risk factors (e.g., social and normative influences). Only sensation seeking increased the risk of susceptibility to e-cigarettes among 10th graders. Overall, by grade level, incidence of susceptibility to e-cigarettes at 12 months did not vary, but risk factor profiles varied substantially.