Cannabis and Bipolar Disorder

Persons with bipolar disorder (BD) commonly use cannabis and have a high prevalence of co-occurring cannabis use disorder (CUD). In addition, persons with BD and co-occurring CUD tend to have earlier onset of symptoms and are more likely to have psychosis, suicide attempts, and other SUDs in comparison to those without CUD. Moreover, convergent evidence indicates that CUD is associated with longitudinal impacts on the course of BD, demonstrating an association with longer and more frequent mood episodes, lower recovery and remission rates, as well as poorer psychosocial functioning; however, abstinence from cannabis may improve clinical outcomes, partly by increasing treatment adherence. Although the impact of CUD on the course of BD is known, there are no published randomized controlled trials so far that have explicitly focused on this comorbidity; therefore, there is no specific evidence to guide the treatment of co-occurring BD and CUD.