Five-Year Outcomes of a School-Based Personality-Focused Prevention Program on Adolescent Substance Use Disorder: A Cluster Randomized Trial.

Objective: Rates of substance use disorders (SUDs) remain significantly above national targets for health promotion and disease prevention in Canada and the United States. This study investigated the 5-year SUD outcomes following a selective drug and alcohol prevention program targeting personality risk factors for adolescent substance misuse.

Methods: The Co-Venture trial is a cluster randomized trial involving 31 high schools in the greater Montreal area that agreed to conduct annual health behavior surveys for 5 years on the entire 7th grade cohort of assenting students enrolled at the school in 2012 or 2013. Half of all schools were randomly assigned to be trained and assisted in the delivery of the personality-targeted PreVenture Program to all eligible 7th grade participants. The intervention consisted of a brief (two-session) group cognitive-behavioral intervention that is delivered in a personality-matched fashion to students who have elevated scores on one of four personality traits linked to early-onset substance misuse: impulsivity, sensation seeking, anxiety sensitivity, or hopelessness.

Results: Mixed-effects multilevel Bayesian models were used to estimate the effect of the intervention on the year-by-year change in probability of SUD. When baseline differences were controlled for, a time-by-intervention interaction revealed positive growth in SUD rate for the control group (b=1.380, SE=0.143, odds ratio=3.97) and reduced growth for the intervention group (b=-0.423, SE=0.173, 95% CI=-0.771, -0.084, odds ratio=0.655), indicating a 35% reduction in the annual increase in SUD rate in the intervention condition relative to the control condition. Group differences in SUD rates were reliably nonzero (95% confidence) at the fourth and fifth year of assessment. Secondary analyses revealed no significant intervention effects on growth of anxiety, depression, or total mental health difficulties over the four follow-up periods.

Conclusions: This study showed for the first time that personality-targeted interventions might protect against longer-term development of SUD.