Online cannabis reduction program helped heavy users cut back, with or without therapist introduction

All participants reduced cannabis consumption frequency and problems at end of treatment (6 weeks) and follow-up (10 weeks). The MET-therapist group showed significantly greater reductions in cannabis quantity vs waitlist. The research assistant group showed greater reductions in cannabis problems vs waitlist. No significant differences between therapist-guided and research assistant conditions. No effects on anxiety, depression, or quality of life.

Pre-registered RCT (NCT04965012). 152 Canadian heavy cannabis users randomized to: (1) MET-therapist guided introduction + 6-week online program, (2) non-MET research assistant introduction + 6-week online program, or (3) psychoeducation waitlist control. The CANreduce program used CBT and motivational interviewing content. Assessments at baseline, 6 weeks, and 10 weeks.

Many heavy cannabis users do not seek treatment due to barriers like cost, wait times, and stigma. This trial shows that an online self-guided program can produce meaningful reductions in use, with the added finding that a brief therapist introduction, while helpful for quantity, is not essential for reducing use frequency.

The finding that the psychoeducation waitlist group also improved suggests that simply engaging with cannabis-related educational materials may prompt behavior change. The online delivery model addresses a critical gap in cannabis treatment access, especially in regions where specialized treatment is unavailable.

Relatively small sample (n=152) across three conditions limits power. 10-week follow-up is short for assessing sustained behavior change. Canadian legal context may not generalize to other jurisdictions. Waitlist improvement complicates interpretation. No biomarker verification of self-reported use.