AIM To evaluate the effectiveness, safety and cost-effectiveness of psychosocial interventions for cannabis use disorder (CUD).

METHODS A systematic review of randomized controlled trials (RCTs; PROSPERO protocol CRD42024553382) of psychosocial interventions for CUD lasting >4 sessions, delivered synchronously, to individuals with CUD aged ≥16 years, in inpatient, outpatient or community-based settings. We searched databases (MEDLINE/PsycInfo/Cochrane CENTRAL) to 12 June 2024. We assessed results using Risk of Bias 2 and conducted pairwise meta-analyses. Primary outcomes were continuous- and point-abstinence and withdrawal intensity at the end of treatment, treatment completion and adverse events.

RESULTS We included 22 RCTs (3304 participants). Relative to an inactive/non-specific comparator, cognitive-behavioural therapy with motivation enhancement (MET-CBT) increased point abstinence [odds ratio (OR) = 18.27; 95% confidence interval (9.00-37.07)] and continuous abstinence [OR = 2.72; (1.20-6.19)], but reduced treatment completion [OR = 0.53; (0.35-0.85)]. Dialectical behavioural/acceptance and commitment therapy increased point abstinence versus inactive/non-specific comparator [OR = 4.34; (1.74-10.80)]. The effect of MET-CBT plus affect management versus MET-CBT on point abstinence was OR = 7.85 (0.38-163.52). The effect of MET-CBT plus abstinence-based contingency management versus MET-CBT on point abstinence was OR = 3.78 (0.83-17.25), and on continuous abstinence OR = 1.81 (0.61-5.41). For MET-CBT plus abstinence-contingency management versus MET-CBT plus attendance-contingency management, the effect on point abstinence was OR = 1.61 (0.72-3.60), and on continuous abstinence OR = 2.04 (0.75-5.58). The effect of community reinforcement on point abstinence was OR = 0.29 (0.04-1.90) versus MET-CBT, and on continuous abstinence OR = 47.36 (16.00-140.21) versus non-specific comparator. Interventions other than MET-CBT may not affect treatment completion. No adverse events were reported. No study reported withdrawal intensity. Two economic evaluations reported higher costs for more complex interventions and contingency management.

CONCLUSIONS Cognitive-behavioural therapy with motivation enhancement and dialectical behavioural/acceptance and commitment therapy may increase abstinence among people with cannabis use disorder relative to an inactive/non-specific comparator. The conclusions remain tentative due to low- to very low-certainty evidence and the small number of studies.