A three-session online harm reduction program called The Illicit Project slowed increases in binge drinking, nicotine, MDMA, cocaine, and prescription drug misuse among Australian high schoolers, but showed limited effects on cannabis use specifically.
School administrators and public health professionals designing substance use prevention programs; researchers studying harm reduction in adolescents.
67% reduction in binge drinking uptake; no effect on cannabis
What the researchers found
The intervention group showed significantly slower increases in binge drinking (OR 0.33), cocaine use (OR 0.06), and prescription drug misuse (OR 0.07) over 12 months compared to controls. Cannabis use showed no significant intervention effect. Drug literacy and harm reduction help-seeking skills remained higher in the intervention group.
Why it matters
School-based substance use programs often show weak effects. This online, neuroscience-based approach demonstrated meaningful reductions across multiple substances in a rigorous trial design, though the lack of cannabis-specific effects is notable.
The numbers in context
950 students across 8 schools. 63% completed 12-month follow-up. Binge drinking OR 0.33 (95% CI 0.12-0.89). Cocaine use OR 0.06 (95% CI 0.01-0.64). Prescription drug misuse OR 0.07 (95% CI 0.01-0.54). Cannabis use: no significant effect (P > 0.5).
How the study worked
Two-arm cluster-randomized controlled trial across 8 secondary schools in New South Wales, Australia. 950 students (mean age 15.9) were assigned to the intervention (5 schools, n=681) or active control (3 schools, n=269). Follow-up at 6 and 12 months.
What this study cannot tell us
Unequal cluster sizes (5 vs 3 schools). 37% attrition at 12 months. Self-reported outcomes. Australian context may not generalize to other countries. Active control received standard health education, not no intervention.
How to read the evidence
Cluster-RCT with active control and 12-month follow-up, though attrition and unequal clusters introduce some uncertainty.
When this study was published
2024 study
The bigger picture
Online harm reduction education may be more effective than traditional approaches for most substances, but cannabis use among teens appears resistant to this type of intervention, suggesting different drivers or cultural factors may be at play.
Questions still open
- Why did the program work for other substances but not cannabis? Would a cannabis-specific module improve effectiveness?
Common questions
What was The Illicit Project?
Why did it not work for cannabis?
Read the original research
An on-line school-based substance use harm reduction programme: The Illicit Project randomized controlled trial results.
Addiction (Abingdon, England), 119(4), 741-752
Citation
Debenham, Jennifer; Birrell, Louise; Champion, Katrina E; Newton, Nicola. (2024). An on-line school-based substance use harm reduction programme: The Illicit Project randomized controlled trial results.. Addiction (Abingdon, England), 119(4), 741-752. https://doi.org/10.1111/add.16403
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