People with bipolar disorder frequently struggle with substance abuse and dependence. Typically, cannabis is the most commonly abused drug in individuals with bipolar disorder. Some investigators have implied that cannabis may actually be mood stabilizing in patients with bipolar disorder. However, the relationships between cannabis use and bipolar disorders are complex and remain incompletely described.

The aim of this study was to identify the characteristics of addiction to cannabis in bipolar patients type I and determine the consequences of cannabis on the expression of bipolar illness and prognosis.

This is a comparative cross-sectional study which included patients followed in the psychiatry department of the G Razi hospital for bipolar disorder type I and for substance dependence according to DSM IV diagnostic criteria. Hetero-questionnaire on sociodemographic variables, clinical and treatment.

The average age was 41 years. The average hospital stay was 9.18 days. 33.33% of patients were monitored regularly. Most patients were single and worked as a day labourer. Cannabis was the most consumed substance. Cannabis use was prior to the expression of psychiatric illness in 55% of cases. The average number of hospitalisation in patients with a cannabis addiction was significantly greater than that observed in the non-addicted group. Similarly, the average number of suicide attempts among patients with cannabis addiction was significantly higher than the group without cannabis addiction.

Aggressive drug abuse treatment immediately after a first psychiatric hospitalisation might decrease rates of recurrence and new cases of cannabis use disorder in the course of bipolar disorder.