Online interventions for cannabis use among adolescents and young adults: Systematic review and meta-analysis

Background Young people present high rates of cannabis use, abuse, and dependence. The United Nations estimates that roughly 3.8% of the global population aged 15-64 years used cannabis at least once in 2017. Cannabis use in young people may impair cognitive skills, interfere with learning, impact relationships, and lead to long term behavioural and psychological consequences. Online cannabis interventions (OCI) are increasingly popular, but their dissemination is not often supported by empirical evidence. Aim To systematically compile and analyse the effectiveness of OCI for the reduction of cannabis use among adolescents and young adults (AYA). Methods Pooled effect sizes of cannabis use between treatment and control groups were estimated. For each comparison, Hedge's g was calculated using a random effects model. Results The search strategy yielded 4531 articles. Of those, a total of 411 articles were retrieved for detailed evaluation resulting in 17 eligible studies (n = 3525). Analyses revealed that online interventions did not significantly reduce cannabis consumption (Hedge's g = -0.061, 95% CI [-0.363] to [-0.242], p = .695) and high heterogeneity was noted (Q = 191.290). More recent studies using structured interventions, daily feedback, AYA centred designs, and peer support, specifically targeting CU seemed to have positive effects to address CU in this population. Conclusions The lack of positive outcomes suggests that more specific and targeted interventions may be necessary to promote cannabis-related behavioural change among young people. These targeted interventions may include structured CU modules, daily feedback, peer support for increased adherence, user-centred design procedures, and input from key stakeholders such as families and service providers.