Can Psychopathology Predict Adolescent Drug Use or Moderate the Effect of a Schoool-Based Drug Use Prevention Program?

Although psychiatric symptoms and drug use are commonly associated with adolescence, the causal relationship has not been fully established. In this study, we sought to identify baseline predictors of adolescent drug use focused on psychopathology and participation in the school-based prevention program #Tamojunto 2.0. We also aimed to assess the moderating effect of mental health in reducing adolescent drug use, which is the primary outcome of the #Tamojunto 2.0 program. A cluster randomized controlled trial with two parallel arms was conducted in 73 Brazilian public schools (37 in the intervention group and 36 in the control group). Baseline and 9-month follow-up measures of 5208 students in the 8th grade—mean age of 13.2 years (SD = 0.8) and equal gender ratio—were assessed. The main outcome variable of the study was adolescents’ past-month drug use at 9-month follow-up. The explanatory variables were past-month drug use, the RCT group, psychopathology, and sociodemographic items (gender, age, and socioeconomic status) at baseline. Findings indicated that besides females, older age, an abnormal score of mental health symptoms, and previous drug use were the most significant predictors of adolescent drug consumption. We found no evidence of a moderating effect of mental health symptoms in reducing drug use because of intervention. These results suggest that strategies for drug use prevention among adolescents should consider abnormal mental health as a predictor of drug use, but not in the case of #Tamojunto 2.0, as a moderator of the intervention effect. Brazilian Register of Clinical Trials: RBR-8cnkwq ( http://www.ensaiosclinicos.gov.br/rg/RBR-8cnkwq/ ).