Résumé·s
Background: Questions remain regarding the consequences of illicit drug use on adolescent adjustment
and the nature of mechanisms that may explain these consequences. In this study, we examined whether
early-onset illicit drug use predicts subsequent academic and psychosocial adjustment and whether
associations are socially-mediated by decreased school engagement and increased peer deviancy.
Method: 4885 adolescents were followed throughout secondary school. We used regressions to determine
whether illicit drug use in grade 7 predicted academic achievement, school dropout, depressive
symptoms, and conduct problems in grades 10–11, adjusting for potential confounders. We used path
analysis to test whether significant associations were mediated by school engagement and peer deviancy
in grade 8.
Results: Illicit drug use predicted conduct problems and school dropout, but not academic achievement
and depressive symptoms. The association between illicit drug use and conduct problems was fully mediated
by increased peer deviancy. The association between illicit drug use and school dropout was partially
mediated by increased peer deviancy, but remained mostly direct. No indirect association via decreased
school engagement was found. Examination of reverse pathways revealed that conduct problems and
academic achievement in grade 7 predicted drug use in grades 10–11. These associations were mediated
by peer deviancy and school engagement (conduct problems only).
Conclusion: Adolescent illicit drug use influences the risk of school dropout and conduct problems in
part by contributing to deviant peer affiliation. Reciprocal social mediation characterizes the association
between drug use and conduct problems. A reverse mechanism best explains the association with
academic achievement.