School program teaches drug resistance, but student cannabis use remains unchanged

This study evaluated the high school version of the Botvin LifeSkills Training program to prevent or reduce adolescent substance use and other problem behaviors. We randomized 50 high schools (N = 2,475 students) in Colorado and Ohio to either a 10-session, teacher-led intervention group (n = 29 schools, n = 1,324 students) or a business-as-usual control group (n = 21 schools, n = 1,151 students). Two cohorts of 9th and 10th grade students completed self-report surveys at pretest, post-test, 1-year follow-up, and 21-month follow-up. Primary outcomes were past 30-day nicotine use and past 30-day cannabis use. Secondary outcomes were other substance use, psychosocial behaviors, academic grades, and intermediate outcomes including attitudes toward substance use and life skills targeted by the intervention. Intent-to-treat analyses used multilevel modeling with multiple imputation to estimate intervention effects on outcomes at each follow-up assessment. At 21-month follow-up, there were significant intervention effects on two intermediate outcomes after correction for multiple comparisons: greater advertising resistance (β = .58, p = .002, 95% CI: .27-.89) and emotion regulation (β = .55, p = .007, 95% CI: .20-.90) for intervention versus control group participants. All other intervention effects were nonsignificant. This large-scale, independent evaluation found significant intervention effects on two mechanisms targeted by the intervention but null effects on all behavioral outcomes. We consider these results in the context of LifeSkills Training program characteristics, developmental trends in substance use behaviors, and potential influences of the COVID-19 pandemic on intervention research with adolescents. https://osf.io/dnz5q/.