An analysis of within-subject and population level risk related to substance use and mental health outcomes among adolescents in the PATH study

Introduction: The objective of this study was to understand how adolescent substance use patterns may lead to negative mental health outcomes. Methods: Data from adolescents (12–17 years old at baseline, Wave 1) who participated in the first 3 waves of the Population Assessment of Health and Tobacco (PATH) study were used. Self-reported data on past 30-day substance use and internalizing/externalizing problems were used to conduct within-subject (fixed-effects model) and population-averaged (GEE model) analyses. Results: In both within-subject and between-subject analyses, the use of other illicit drugs (e.g., opioids, cocaine, prescription drugs for non-medical use) was positively associated with internalizing problems (within-subject estimate, AOR: 1.65, 95 % CI = 1.36–2.01; between-subject estimate, AOR: 1.53, 95 % CI = 1.32–1.78) and alcohol use was positively associated with externalizing problems (within-subject estimate, AOR: 1.66, 95 % CI = 1.43–1.93; between-subject estimate, AOR: 1.67, 95 % CI = 1.48–1.89). Additionally, within-subject analysis suggested that alcohol, marijuana, and other illicit drugs were associated with increased odds of comorbid internalizing and externalizing problems (ranging from marijuana, AOR: 1.18, - alcohol, AOR: 1.58). Discussion: Using within-subject and between-subject comparisons, this study demonstrated associations between adolescent substance use and internalizing and externalizing problems. Results suggest not only the need for individual level assessment and early intervention, but also the development and implementation of public health policy aimed at preventing or mitigating the negative effects of substance use in adolescence to promote improved mental health outcomes for this at-risk group.