LAUSR

INTRODUCTION Alcohol, nicotine, and marijuana are the three most widely used substances among adolescents and young adults, with co-use of multiple substances being common. Few longitudinal studies have examined risk factors of alcohol, marijuana, and nicotine poly-substance use. We examined frequency of alcohol, marijuana, and cigarette poly-substance use over time and how key risk factors contribute to this substance use during adolescence and young adulthood. METHODS Participants (N = 1263 9th and 10th graders) were oversampled for ever-smoking a cigarette at baseline from 16 Chicago-area high schools between 2004 and 2006. Many participants progressed to heavier cigarette use, as well as alcohol and marijuana use over time. Participants completed questionnaires assessing substance use and psychosocial factors at baseline, 6-, 15-, 24-, 33-months, and 5-, 6-, and 7-years. RESULTS Longitudinal multi-level models demonstrated that at baseline and over time, more depression symptoms, more anxiety symptoms, negative mood regulation expectancies, and lower grade point average (GPA) were each associated with more poly-substance use over time. In addition, there were a number of interaction effects of gender (e.g., depression was related to substance use in males) and developmental stage moderated these relationships. CONCLUSIONS Depression, anxiety, negative mood regulation expectancies, and GPA all significantly influence both initial and longitudinal levels of substance use across adolescence and young adulthood. Our findings underscore the importance of identifying and treating youth with depression and anxiety symptoms, as well as providing resources early for those struggling in school in order to help with substance use prevention and intervention efforts.