Design and Evaluation of a neuroscience-based, harm reduction program to prevent alcohol and illicit substance use among late adolescents: An RCT of the Illicit Project

Background: Alcohol and illicit substance use are major contributors of global morbidity and mortality, and harm falls disproportionately on young people. The prevention of risky substance use during adolescence is critical. There are limited age-appropriate programs that target late adolescents aged 16-19 years, despite this representing the age of initiation and escalation of substance use. The Illicit Project is a neuroscience-based, harm minimisation program designed to upskill late adolescents in the senior years of school. The current study outlines the iterative development and evaluation of the program with Australian youth.

Methods: A cluster randomised controlled trial was conducted involving 950 students (Mage = 15.9 years SD = 0.68; 60% Female) from eight secondary schools in New South Wales, Australia. Five schools were received the Illicit Project intervention and three schools received health education as usual in the active control group. All students completed a self-report survey at baseline and 6-months post-baseline and intervention students completed a program evaluation su rvey. Outcomes include alcohol and illicit substance use, alcohol related harms and drug literacy levels (knowledge and skills to minimize the harms of substance use) and were analyzed using multilevel mixed effects models.

Results: At 6-months post baseline, individuals in the intervention group were less likely to engage in weekly binge drinking (OR=0.56), early onset cannabis use (OR=0.35), ecstasy use (OR=0.16) and nicotine product use (OR=0.59) compared to those in the control group. Students in the intervention group were less likely to have experience alcohol related harms (OR=0.57) and more likely to have higher drug literacy scores (β=2.44) at follow-up. The results are limited by higher attrition in the intervention group compared to the control group.

Conclusion: This rigorous cluster randomized controlled trial supports the effectiveness of newly developed, neuroscience-based program, the Illicit Project. The next steps include implementation trials, adaptation and program upscale.