Marker or mediator? The effects of adolescent substance use on young adult educational attainment

Aims We tested the effects of adolescent substance use on college attendance and completion by young adulthood in the context of the behavioral and familial risk factors that influence substance use. Design, setting and participants Longitudinal data were collected from a community sample of children of alcoholics (248) and matched controls (206) at three adolescent assessments (mu(age) = 13-15) and a long-term follow-up in young adulthood (mu(age) = 25). Measurements College attendance and degree completion by age 25 were self-reported in young adulthood. During adolescence, self-reports of alcohol and drug use were assessed with log-transformed quantity/frequency measures; substance use risk factors [e.g. parental monitoring, externalizing and internalizing symptoms and Diagnostic and Statistical Manual version III (DSM-III) diagnosis of parental alcoholism] were assessed by both self- and parent-report, and adolescent reading achievement was assessed using a standardized assessment of reading achievement (Wide Range Achievement Test). Findings Using growth curve modeling, we found that mean levels and growth in adolescent substance use mark, or identify, those adolescents who are at risk for reduced odds of attending and completing college. Moreover, adolescent substance use was not merely a marker of risk, in that growth in drug use (but not alcohol use) significantly mediated the effects of parental alcoholism and early externalizing behavior on later college completion, partially explaining the effects of these risk factors on college completion. Conclusions The current study provides evidence for both the marker and the mediator hypotheses, and identifies multiple pathways to higher educational attainment. The findings point to the importance of studying the effects of adolescent substance use in a broader developmental context of its correlated risk factors to specify more effectively the key pathways to later developmental outcomes.