Long-term effects of two childhood psychosocial interventions on adolescent delinquency, substance use, and antisocial behavior: a cluster randomized controlled trial

Abstract

Examine the long-term effects of two childhood universal prevention programs on adolescent delinquency, substance use, and antisocial behavior. The cluster randomized controlled trial involved 56 schools and 1,675 children in Zurich, Switzerland. Two evidence-based interventions, namely the social-emotional skills program Promoting Alternative Thinking Strategies (PATHS) and the cognitive-behavioral parenting program Triple P, were implemented during the first two years of primary school, at ages 7 and 8 years. Outcomes were measured at ages 13 and 15 years, and included youth self-reports and teacher assessments. Multilevel models were used to account for the clustered nature of the interventions. Effects were estimated with the inclusion of baseline covariates. Across 13 outcomes related to delinquency, substance use, and antisocial behavior at ages 13 and 15 years, only two non-negligible effects were found. The first was a reduced prevalence of police contacts in the PATHS condition [effect size (ES) = −0.225). The second was a difference in competent conflict resolution skills in the combined PATHS + Triple P condition compared to the context (ES = 0.259), but in the unexpected direction: participants in the combined treatment appeared to be less competent than their control group peers. All other effects were either statistically non-significant or negligible in size (i.e., ES < |0.200|). Even “evidence-based” interventions may have few long-term effects on delinquency, substance use, and antisocial behavior. Our findings add to the small literature on the long-term effectiveness of early universal prevention in field settings.