Substance Use Among Middle School Adolescents: Association with Family Members' and Peers' Substance Use and the Mediating Role of School and Mental Difficulties.

Objective: We assessed the associations of substance (alcohol, tobacco, cannabis, and other illicit drugs) use of adolescents with that of their family members (father, mother, step-parent, brothers/sisters, and grandparents) and peers, and the mediating role of school and mental difficulties (SMDs) which remained insufficiently addressed.

Methods: This cross-sectional population-based study included 1,559 middle-school adolescents in France (mean age = 13.5 ± 1.3, 778 boys, 781 girls). They completed a questionnaire including socioeconomic features (nationality, family structure and parents' education, occupation, and income), substance use, cumulative number of substance use of family members (father, mother, step-parent, brothers/sisters, and grandparents) and peers (noted familySUcn and peerSUcn), SMDs (grade repetition, suffered physical/verbal violence, sexual abuse, lack of family/peer support, depressive symptoms, suicide attempt, and age at onset). Data were analyzed using logistic regression models and Kaplan-Meier estimates.

Results: Most adolescents had familySUcn 1-2, 3-5, and ≥ 6 (39.1%, 23.0%, and 4.5%, respectively) and peerSUcn 1-2 and ≥ 3 (36.1% and 13.0%, respectively). Strong dose-effect associations were found between all substance use and familySUcn and peerSUcn (odds ratio adjusted for sex, age, and socioeconomic features reaching 13.44 and 9.90, respectively, most with p < .001). SMDs explained more the associations of all substance use with familySUcn than with peerSUcn (contributions reaching 69% and 34%, respectively). The proportion of subjects without each substance use decreased with age more quickly among the adolescents with higher familySUcn or peerSUcn.

Conclusions: Early prevention reducing familySUcn, peerSUcn and SMDs among adolescents and their families may reduce efficiently initiation and regular use of substances during adolescents' life course.