Polysubstance Use Trajectories and Social-Ecological Predictors in a Multi-Ethnic Sample of Adolescents

Background: Substance use—including the use and co-use of alcohol, cigarettes, and illicit drugs—often emerges in adolescence. However, the longitudinal structure of polysubstance use and its social-ecological predictors are less understood. We examined (a) higher-order trajectories of polysubstance use (encompassing alcohol, cigarette, and illicit drug use) and (b) their associations with individual- and family-level factors. Methods: Participants were 568 eighth- and tenth graders (M age = 14.46; 50.5% girls) from Miami-Dade County, FL, and Prince George’s County, MD, in a six-wave longitudinal study on alcohol use. Adolescents reported age, sex, race/ethnicity, attention problems, positive parenting, and family structure. Latent growth curve modeling was used. Results: Racial/ethnic composition was 40.8% Hispanic, 35.0% non-Hispanic Black, 6.9% non-Hispanic White, 10.6% others, and 6.7% multiracial. Results indicated the presence of higher-order polysubstance trajectories comprising individual alcohol, cigarette, and illicit drug use, which increased linearly over time. Polysubstance use trajectories were predicted by both individual- and family-level factors. For instance, Black, Hispanic, other, and multiracial adolescents evidenced less steep increases in polysubstance use than White adolescents (average β s = -0.25) and positive parenting predicted lower baseline polysubstance use (β = -0.11, p < 0.05). We also found unique associations with individual substance use trajectories; for example, single-parent households predicted steeper cigarette-use slope (β = 0.08, p < 0.05), and attention problems predicted higher baseline alcohol-use (β = 0.10, p < 0.05). Age was associated with most trajectories, whereas sex was not associated with any. Conclusion: Findings highlight the need to integrate both overarching and substance-specific risk factors into treatment, prevention, and policy efforts to address adolescent substance use.