The role of normative beliefs in the mediation of a school-based drug prevention program: A secondary analysis of the #Tamojunto cluster-randomized trial

AIMS: To investigate the mediating effects of normative beliefs of drug use on the effects of the #Tamojunto school-based prevention program (Unplugged). DESIGN: Secondary analysis of a cluster randomized controlled trial. SETTING: Brazil. Participants: A total of 6,391 adolescents (12.68 y.o) from 72 public schools in 6 Brazilian cities. Intervention: Schools were assigned to an experimental condition (#Tamojunto curriculum) or a control condition (no prevention program). Measurements: Baseline data were collected prior to program implementation, and follow-up data were collected 9 and 21 months later. The substances examined were alcohol (including binge drinking), tobacco, marijuana and inhalants. Five in-parallel mediation models evaluated whether the positive and negative beliefs were mediators of the likely effects of the intervention on drug use. FINDINGS: Lack of evidences regarding differences in normative beliefs or drug use were found between the intervention and control groups. However, there was a clear association between negative drug beliefs and lower consumption (i.e. OR = 0.78; 95% CI 0.70; 0.87, for cannabis use) as well as between positive drug beliefs and higher consumption (i.e. OR = 1.77; 95% CI 1.56; 2.02, for cannabis use) independent of the assigned group. CONCLUSIONS: These results suggest that there is a lack of evidence that the program impact the normative beliefs, as proposed by the theoretical model of the program, suggesting that modifications are needed to produce the intended effect of the program. Negative normative beliefs seem to be a potential protective factor for drug use, but the program’s effect itself on drug use via normative beliefs was not found to be statistically significant. Program activities intended to affect normative beliefs should be improved.