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

The takeaway

In a randomized trial of 152 Canadian heavy cannabis users, an online self-guided treatment program reduced cannabis use frequency and problems across all groups, with therapist-guided introduction providing extra benefit for reducing quantity but not frequency.

Heavy cannabis users interested in cutting back, and clinicians looking for scalable cannabis treatment options.

All groups reduced cannabis use frequency and problems, including the psychoeducation control

What the researchers found

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.

Why it matters

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 numbers in context

152 participants randomized across 3 conditions. All groups reduced cannabis consumption days and problems at 6 and 10 weeks. MET-therapist group: greater quantity reduction vs waitlist. RA group: greater problem reduction vs waitlist. No significant differences between the two active conditions. No effects on anxiety, depression, or QoL.

How the study worked

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.

What this study cannot tell us

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.

How to read the evidence

Pre-registered RCT with three conditions and follow-up, though limited by small sample, short follow-up, and self-reported outcomes.

When this study was published

Published in 2026.

The bigger picture

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.

Questions still open

Would longer-term follow-up show maintained benefits? Could the program work as a standalone tool without any human contact? Would integration with primary care improve outcomes further?

Common questions

Can an online program help reduce cannabis use?

Yes. In this trial, the Canadian CANreduce program reduced cannabis consumption days and related problems at both 6 and 10 weeks across all groups, including those with only psychoeducation.

Is a therapist needed?

A brief motivational therapist introduction helped reduce the quantity consumed but was not necessary for reducing use frequency or problems. The self-guided program alone showed benefits.

Read the original research

Evidence-based therapist guided introduction to online heavy cannabis use treatment in Canadian adults: a Randomized Controlled Trial (RCT).

Journal of cannabis research, 8(1), 26

View on PubMed ↗Publisher’s paper ↗

Citation

Rysen, Karli K; Carusone, Julian M; Wardell, Jeffrey D; Schaub, Michael P; Wenger, Andreas; Wallbridge, Harold; Edgerton, Jason D; Kruk, Richard; Mackenzie, Corey S; Keough, Matthew T. (2026). Evidence-based therapist guided introduction to online heavy cannabis use treatment in Canadian adults: a Randomized Controlled Trial (RCT).. Journal of cannabis research, 8(1), 26. https://doi.org/10.1186/s42238-025-00378-5