ICan, an Internet-based intervention to reduce cannabis use: study protocol for a randomized controlled trial

BACKGROUND: Heavy cannabis use is associated with adverse physical and mental health effects. Despite available effective treatments, the majority of heavy cannabis users does not seek professional help. Web-based interventions can provide an alternative for cannabis users who are reluctant to seek professional help. Several web-based cannabis interventions are effective in reducing cannabis use; however, the effect sizes are typically small and attrition rates are typically high. This suggests that web-based programs can be an effective cannabis use intervention for some, while others may need additional substance use treatment after completing a web-based intervention. Therefore, it is important that web-based interventions do not solely focus on reducing cannabis use, but also on improving attitudes towards substance use treatment. The Screening Brief Intervention and Referral to Treatment (SBIRT) approach appears to be well suited for the purpose of reducing cannabis use and improving substance use treatment utilization. Based on the SBIRT approach—and based on cognitive behavioral therapy (CBT) and motivational interviewing (MI)—we developed the Internet-based cannabis reduction intervention ICan. METHODS/DESIGN: This protocol paper presents the design of a randomized controlled trial (RCT) in which we evaluate the effectiveness of the ICan intervention compared to four online modules of educational information on cannabis in a sample of Dutch frequent cannabis users. The primary outcome measure is frequency of cannabis use. Secondary outcome measures include the quantity of cannabis used (grams), the attitudes towards seeking help and the number of participants who enter specialized treatment services for cannabis use-related problems. DISCUSSION: To the best of our knowledge, ICan is the first Internet-based intervention for cannabis users that combines screening, a brief intervention—based on CBT and MI—and referral to treatment options. TRIAL REGISTRATION: The study is registered in the Netherlands Trial Register; identifier NL7668. Registered on 17 April 2019.