Date of Award

Spring 5-2019

Degree Name

Doctor of Philosophy (PhD)

Advisor(s)

MELISSA HARRELL, PHD

Second Advisor

ANDREW SPRINGER, DRPH

Third Advisor

BAOJIANG CHEN, PHD

Abstract

Due to the pace of legal changes in marijuana policy, shifting trends in marijuana use, and emerging products in the tobacco product marketplace (e.g., ecigarettes), the cycle of risk between marijuana and tobacco use is not currently wellunderstood. I used longitudinal data from two parallel rapid response surveillance studies of youth (aged 12-19 years) and young adults (aged 18-25 years) living in the five counties (Bexar, Dallas, Harris, Tarrant, and Travis) that surround the four largest cities in Texas (Austin, Houston, San Antonio, and Dallas/Fort Worth). I used Generalized Linear Mixed Models (GLMMs) and six-panel cross-lagged regression models to analyze temporal precedence in use and dual use of these products over time (2014 to 2017). Overall, I found dual use to be more common among adolescents than young adults and tobacco and marijuana use and dual use to rise during adolescence and gradually fall during young adulthood. I identified reciprocal temporal relationships between both substances for adolescents and young adults, but marijuana use was particularly predictive of subsequent tobacco use among adolescents. Dual marijuana and tobacco use decreased throughout young adulthood, or at least until age 25, but single product use remained common. I advocate for distinct, developmentally-appropriate interventions that focus on both the use of marijuana and tobacco for sustainable prevention and cessation.

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