Comorbid Cannabis Use Disorder with Major Depression and Generalized Anxiety Disorder: A Systematic Review with Meta-analysis of Nationally Representative Epidemiological Surveys

Background: Studies have shown a high degree of comorbidity between cannabis use disorder (CUD) and other mental illnesses. However, there is a paucity of research on the comorbidity between CUD with major depression (MD) and generalized anxiety disorder (GAD). This systematic review with meta-analysis aimed to assess the prevalence and strength of association between co-morbid CUD with MD and GAD. Methods: An extensive search of Medline, CINAHL, PsycINFO, EMBASE, and grey literature were conducted to cover articles published between January 1st, 1980, and July 31st, 2020. Inclusion criteria were publications in English Language, original research, nationally representative samples, and non-clinical randomly selected adult populations. A systematic review and meta-analysis for the prevalence and ORs for comorbid CUD with MD or GAD were done. Results: A total of 67 articles were identified by the electronic searches. A full-text review yielded 8 publications on nationally representative epidemiological surveys. 12-month and lifetime comorbidity estimates were extracted and used for the meta-analysis. CUD was strongly associated with MDE (OR 3.22; 2.31 - 4.49) and with GAD (OR 2.99; 2.14 - 4.16). Limitations: Limitations of this study include the heterogeneity observed due to the combination of studies from different geographic regions with different modifications of diagnostic criteria and varied response rates. This was addressed with a random-effects model. Conclusion: This review confirms the evidence of high prevalence and a 3-fold comorbid association between CUD with MD and CUD with GAD. Implementation of evidence-based policy interventions with effective, integrated management of comorbid CUDs with psychiatric disorders may contribute to positive patient outcomes.