MONTRÉAL, December 18, 2025 – A brief cognitive-behavioural intervention delivered in early high school can significantly reduce the escalation of adolescent substance use. These new findings, published today in JAMA Network Open by Postdoctoral fellow Samantha Lynch and Dr. Patricia Conrod, Professorand Clinical psychologist, Canada Research Chair in Preventive Mental Health and Addiction and researcher at the Centre de recherche Azrieli du CHU Sainte-Justine, confirm and deepen existing evidence on the program’s effectiveness.
The findings come from a large-scale randomized clinical trial conducted in 31 high schools with more than 3,800 students across the Greater Montreal area. They show that the PreVenture program, which helps youth explore their personality and learn to manage certain traits - impulsivity, sensation seeking, hopelessness, and anxiety sensitivity—significantly slows the increase in alcohol, cannabis, tobacco, and multiple illicit substance use throughout high school.
New analyses reveal that students in schools that delivered the PreVenture program showed much smaller increases in substance use over the four-year follow-up, compared to students in schools without the program:
- 25% reduced annual growth in frequency of cannabis use, meaning students were far less likely to escalate their use over time.
- 21% reduced annual growth in tobacco smoking, highlighting meaningful prevention of early nicotine use.
- 8% reduced annual growth in alcohol use, reflecting a modest but meaningful delay in adopting drinking habits.
- 44% reduced annual growth in multiple illicit substance use, a particularly impactful finding given the risks of combined use.
Substance use typically begins and escalates during adolescence, and early, frequent or multiple substance use is strongly linked to later substance use disorders, overdoses, and mental health concerns.
“Our findings show that a very brief, targeted intervention delivered in schools can meaningfully alter the developmental trajectory of substance use during a critical period of adolescence,” said Dr. Samantha Lynch, lead author. “By delaying increases in use - especially cannabis and multiple substance - we can reduce the likelihood that youth will adopt harmful patterns that place them at risk of addiction and overdose.”
New Follow-Up into Adulthood
The research team is now launching a follow-up study to reconnect with the same cohort, now approximately 25-26 years old, to determine whether these early reductions in substance use translate into healthier outcomes in young adulthood. This follow-up will assess patterns of substance use, including alcohol, cannabis use, smoking and vaping, along with mental health and other important health and wellbeing factors.
“With multiple randomised trials demonstrating effectiveness of this program on youth substance use, communities around the world are now accessing training and program materials to deliver the program. This next phase will allow us to answer a central question in prevention science: do early, targeted interventions produce lasting benefits into adulthood?” said Dr. Conrod.
Quote
"Across Chicago’s Northwest Suburbs, OMNI has consistently found that students, schools, and facilitators love the PreVenture program. A key component of effective prevention is building excitement and buy-in, and PreVenture does exactly that. It is a unique program that recognizes students for who they are and supports their strengths. At the same time, it remains a highly effective, evidence-based prevention program that is practical and easy to implement." - Maykala Ratcliffe, Omni Youth Services
About the Centre de recherche Azrieli du CHU Sainte-Justine
The Centre de recherche Azrieli du CHU Sainte-Justine is a leading mother-child research institution affiliated with the Université de Montréal. It brings together 295 research investigators, including over 160 clinician-scientists, as well as more than 580 graduate and postgraduate students focused on finding innovative prevention means, faster and less invasive treatments, as well as personalized approaches to medicine. The centre is an integral part of CHU Sainte-Justine, which is the largest mother-child centre in Canada.
recherche.chusj.org
About the study
The CoVenture Trial is a cluster randomized trial that was funded by the Canadian Institutes of Health Research, and aimed to test whether a school-based preventive mental health intervention (The PreVenture Program) could reduce risk for substance use disorder over a 5-year period in adolescence. The trial involved over 3,800 students who completed a brief self-report personality questionnaire in the 7th grade assessing impulsivity, sensation seeking, anxiety sensitivity and hopelessness. Schools were randomly assigned to be trained and assisted in delivering personality-targeted brief cognitive behavioural interventions to student who reported elevated scores on one of these four traits. Interventions were two, 90-minute group workshops delivered in the 7th grade. All students were followed every year for five years on school-based digital assessments. Dr. Conrod supports an international team of researchers and knowledge transfer experts dedicated to worldwide dissemination and evaluation of this program (www.preventureprogram.com).
About the authors
Samantha Lynch is a postdoctoral fellow at the Université de Montréal and Centre de recherche Azrieli du CHU Sainte-Justine, specializing in the development and prevention of adolescent mental health and substance-use problems.
Dr. Patricia Conrod, psychologist, is a Professor of Psychiatry and Addiction at the Université de Montréal and holds the Canada Research Chair in Preventive Mental Health and Addiction, and the Fondation Julien/Marcelle et Jean Coutu Chair in Social and Community Pediatrics. She also co-directs CHU Sainte-Justine's Centre IMAGINE, a pediatric brain imaging centre.