The prevalence and clinical correlates of cannabis use and cannabis use disorder among patients with bipolar disorder: A systematic review with meta-analysis and meta-regression

Bipolar disorder (BD) is commonly associated with comorbidities, especially substance use disorders. In light of this, the present review aimed to investigate the prevalence and clinical correlates of cannabis use in BD. Studies evaluating the prevalence of cannabis use among patients with BD and studies reporting a dichotomous sample of patients with cannabis use compared to those without the use were included. Meta-analyses using random-effects models were performed, and sources of heterogeneity were explored using meta-regression. The search resulted in 2918 publications, of which 53 were included. The prevalence of cannabis use was 24% (95%CI:18–29; k = 35; n = 51,756). Cannabis use was significantly associated with being younger, male, and single; having fewer years of education and an earlier onset of affective symptoms; and lifetime psychotic symptoms, suicide attempts, and use of tobacco, alcohol, and other substances. In conclusion, cannabis use present in almost one-quarter of patients with BD and is associated with factors that are highly relevant for both clinical practice and public health.