Dutch School-Based Drug Prevention Program Had No Effect on Teen Substance Use

This was a randomized clustered trial involving 3,784 students aged 11-15 across 23 Dutch secondary schools. Schools were randomly assigned to one of three conditions: e-learning intervention, integral intervention (e-learning plus school policy and parent components), or control. Students completed digital questionnaires before the intervention and at 32-month follow-up. The primary outcomes were new incidences of substance use.

This study is a reminder that well-intentioned prevention programs do not always work. The null result raises questions about whether the specific program content, delivery method, or implementation quality was insufficient, or whether school-based prevention programs in general face fundamental challenges in changing adolescent substance use behavior.

School-based substance use prevention programs have a mixed track record. While some programs have shown modest effects, many well-designed evaluations find null results. These findings highlight the importance of rigorous evaluation before implementing prevention programs at scale and the need to identify what program elements actually drive behavior change.

The study measured incidence (new use) rather than changes in frequency among existing users. The 32-month follow-up may have missed shorter-term effects that faded. Implementation quality across schools was not closely monitored, and the authors note the program may have been implemented inadequately at some sites.