The effectiveness of motivational intervention in helping cannabis users to quit : a systematic review

Abstract

Background: The increasing trend in the number of cannabis consumers is a public health concern and increases the financial cost to our society. Motivational interventions (MI) have the potential to reduce cannabis use and symptoms of cannabis use disorders in different setting. The aim of this systematic review is to evaluate the effectiveness of MI in helping cannabis users to initiate change and quitting of cannabis use. Methodology: A literature review was performed using the online databases PubMed and Google Scholar by using keywords including “motivational interviewing” or “motivational enhancement therapy” and “cannabis users” or “marijuana users” with no year restrictions. Further manual reference searches were done to review randomized controlled trials (RCTs) of MI. The quality of studies was assessed based on the CONSORT checklist. Findings: Ten relevant studies were included in the review. Overall, MI appeared to be associated with reductions of cannabis use frequency and symptoms of cannabis dependence compared with delayed treatment control groups. Six studies reported significantly fewer days of cannabis use in the intervention compared to the delayed treatment control groups. Only five studies reported declines in the number of dependence symptoms compared to delayed treatment control groups. However, when the intervention groups were compared with the other comparative treatment groups no significant differences were observed. Studies were mostly small with limited generalizability. Conclusion: While MI could be effective in reducing cannabis use, it is unclear whether the findings of this review can apply to setting with the low prevalence of cannabis use. Future research requires larger RCTs and assessment of the effectiveness of various components of MI that may influence motivation to change in the long term.