The effectiveness of psychological interventions delivered by health professionals for adult cannabis use in community settings: a systematic review and meta-analysis.

Introduction: Cannabis is one of the most widely used psychoactive substances and is associated with negative consequences affecting physical and mental health, cognition, quality of life, functional outcomes, employment, and interpersonal relationships. The impact of cannabis use varies between individuals and is not necessarily related to consumption quantity or frequency. This variability underscores the importance of outcome measures beyond consumption patterns to capture real-world functional impact. Reducing the health and social consequences of substance use remains a core objective of many national drug strategies. Effective treatments for cannabis use are essential, as no pharmacological therapy is approved; psychosocial interventions remain the primary approach. This systematic review and meta-analysis aimed to summarize the evidence on psychological interventions delivered by health professionals in a community setting for adults with problematic cannabis use, focusing on outcomes related to cannabis-related problems and severity of dependence. Methods: A systematic search was conducted following the PRISMA guidelines. Articles were included if they quantitatively examined the efficacy of psychosocial interventions of at least two sessions, delivered by health professionals in community settings, among adult cannabis users. Meta-analyses were performed using random-effects models. Heterogeneity was assessed with I², and publication bias with Egger's test. The risk of bias was assessed using the RoB 2 tool for randomized trials. Results: A total of fifteen studies were included, and the risk of bias was ranging from "some concerns" to "high". Regarding cannabis-related problems and the severity of cannabis dependence, cognitive-behavioral therapy (CBT) was the only intervention associated with a small, temporary effect relative to active control groups (SMD=-0.23 to -0.36). Compared with inactive controls, CBT combined with motivational approaches showed small post-intervention benefits on cannabis-related problems (SMD=-0.39) and moderate to large effects on cannabis dependence (SMD=-0.69 to -0.88). However, most comparisons were non-significant, and most significant findings derived from a single study. Conclusion: Evidence supporting the effectiveness of psychological interventions for problematic cannabis use remains limited. Findings should be interpreted with caution, highlight the need for further high-quality research focusing on clinically meaningful outcomes beyond consumption patterns, as well as on the development and rigorous evaluation of innovative interventions targeting cannabis-related harms.