Cannabis Use Disorder Associated With an Increased Risk of Subsequent Major Depressive and Bipolar Disorders

Associations between cannabis use disorder (CUD) and affective psychiatric illnesses are understudied. Researchers analyzed registry data from Danish persons ≥16 years old between 1995 and 2021 to examine the associations between CUD diagnosis and subsequent diagnoses of major depressive disorder (unipolar depression) and bipolar disorder, including psychotic and non-psychotic subtypes of each illness.

• Of the 6,651,765 persons (50 percent female) analyzed, 1 percent (n=60,696) were diagnosed with CUD and 4 percent (n=260,746) were diagnosed with an affective disorder over the study period.
• There was an increased risk of developing both psychotic depression (adjusted hazard ratio [aHR], 1.97) and nonpsychotic depression (aHR, 1.83) among persons with CUD compared with those without CUD.
• There was an increased risk of developing psychotic bipolar disorder (aHR, 4.05) and nonpsychotic bipolar disorder (aHR, 2.96 for men; aHR, 2.60 for women) among persons with CUD compared with those without CUD.
• Risk of developing an affective illness was highest within the first 6 months of CUD diagnosis for both unipolar depression and bipolar disorder, but the risk of developing either affective illness disorder remained elevated for 10 years following CUD diagnosis.

Comments: These data suggest that CUD is associated with an increased risk of developing both psychotic and nonpsychotic major depressive disorder and bipolar disorder, although a causal link has not been established. As cannabis use and CUD become increasingly prevalent, clinicians should be aware that patients with CUD may have higher likelihood of developing affective illnesses.

Carrie Mintz, MD

Reference: Jefsen OH, Erlangsen A, Nordentoft M, Hjorthøj C. Cannabis use disorder and subsequent risk of psychotic and nonpsychotic unipolar depression and bipolar disorder. JAMA Psychiatry. 2023;80(8):803–810.