Motivational interviewing (MI) is widely used in the addiction field, notably to address unhealthy alcohol use, for which there is good evidence of efficacy. There is no gold standard to treat cannabis use disorder (CUD). Researchers reviewed the evidence of efficacy of MI for addressing CUD. They identified 40 studies (randomized trials and open-label trials) focusing on adults and adolescents to include in the systematic review. Studied interventions included in-person and electronic interventions, and brief and more extended interventions (motivational enhancement therapy).
- Overall, 32 of the 40 studies included in the review showed evidence for efficacy of MI for CUD.
- Meta-analyses were conducted with a 3-month follow-up endpoint.
- MI was associated with greater odds of cannabis abstinence among adults (odds ratio [OR], 3.84; 2 studies included in the meta-analysis) and adolescents (OR, 2.02; 4 studies).
- In adults, MI was associated with a reduced frequency of cannabis use (mean difference -3.9 days in a month; 6 studies) and quantity of use (mean difference 0.69 joints in a day; 6 studies), but not among adolescents (5 studies for quantity of use, 7 for frequency of use).
- There was no effect of MI found for CUD symptoms (2 studies for adults, 4 for adolescents).
Comments: A limited number of studies was included in this meta-analysis and the evidence of efficacy is most robust for reducing cannabis use among adults (6 studies). It is more difficult to conclude about evidence of efficacy among adolescents and on abstinence and CUD symptoms due to the limited number of studies and null results. This systematic review considered a broad range of MI-based interventions and does not provide an insight on potential differences across interventions.
Nicolas Bertholet, MD, MSc
Reference: Calomarde-Gómez C, Jiménez-Fernández B, Balcells-Oliveró M, et al. Motivational interviewing for cannabis use disorders: a systematic review and meta-analysis. Eur Addict Res. 2021;27(6):413–427.