Cannabis is a frequently-used psychoactive substance. While the majority of individuals can use cannabis without experiencing problems, a small minority of people develop cannabis problems. Despite the small-to-medium reported effect sizes of cognitive behavioural therapy (CBT) and motivational enhancement therapy (MET) treatments for cannabis misuse, many cannabis users do not seek treatment. Online CBT/MET programs have the potential to be cost-effective and accessible, and offer a less stigmatizing option for treatment. These programs may also help capture cannabis users who experience subclinical problems, who are not captured by traditional treatment. Existing treatment programs also need to be adapted to maximize participant retention and increase treatment completion, as many current cannabis use treatment programs have significant drop-out rates. Hence, the goal of the proposed randomized controlled trial (RCT) is to examine the efficacy of an online evidence-based CBT/MET treatment program. Outcomes of a combined CBT/MET treatment program will be compared to a CBT-only treatment program and a waitlist control. This research will provide insight into the novel contribution of MET to online CBT treatment programs for cannabis misuse.

The researchers are hoping to recruit 303 participants for this study from Central and Eastern Canada. Participants will be randomly assigned to one of the treatment groups (i.e., CBT with MET, CBT without MET) or the psychoeducational control group. Individuals in either treatment group will be given 6 weeks to work through 8 online modules. Throughout the modules, participants will identify goals related to cannabis use, learn strategies to cope with cannabis cravings, triggers, and social pressures and learn to prevent relapse. Participants randomly assigned to the control (i.e., psychoeducation) will receive links to websites that provide general psychoeducation about cannabis use and wellbeing. All participants will complete online assessment measures at baseline, end of treatment, and at follow up approximately one month later (i.e., 0 weeks, 6 weeks, 10 weeks) in order to assess the efficacy of the treatment. At the end of the study, individuals in the control group will be given access to the CBT without MET treatment.

Inclusion Criteria:

• Ages 19+
• Living in Manitoba or Ontario, Canada
• Reporting moderate difficulties with cannabis as indicated by a score of 8 or more on the Cannabis Use Disorders Identification Test - Revised (CUDIT-R; Adamson et al., 2010)
• Fluency in English
• Having weekly Internet access with a device that allows for video connection
• Self-report at least a 6 out of 10 on a Likert-type scale for motivation to reduce cannabis use (i.e., how important it is to reduce cannabis use)

Exclusion Criteria:

• Self-reported engagement in other psychological or pharmacological treatments for cannabis use
• Elevated suicidality, as defined by scoring greater than minimal risk on a screener
• Current serious psychiatric disorders or history of psychosis, schizophrenia, bipolar disorder
• Are a woman who is currently pregnant or breastfeeding