Lifetime cocaine use is a potential predictor for conversion from major depressive disorder to bipolar disorder: A prospective study

Aim We aimed to identify whether lifetime cocaine use is a risk factor for conversion from major depressive disorder (MDD) to bipolar disorder (BD) in an outpatient sample of adults. Methods This prospective cohort study included 585 subjects aged 18 to 60 years who had been diagnosed with MDD as assessed by the Mini International Neuropsychiatric Interview (MINI‐Plus) at baseline (2012–2015). Subjects were reassessed a mean of 3 years later (2017–2018) for potential conversion to BD as assessed by the MINI‐Plus. Lifetime cocaine use was assessed using the Alcohol, Smoking, and Substance Involvement Screening Test. Results In the second wave, we had 117 (20%) losses, and 468 patients were reassessed. The rate of conversion from MDD to BD in 3 years was 12.4% (n = 58). A logistic regression analysis showed that the risk for conversion from MDD to BD was 3.41‐fold higher (95% confidence interval, 1.11–10.43) in subjects who reported lifetime cocaine use at baseline as compared to individuals who did not report lifetime cocaine use at baseline, after adjusting for demographic and clinical confounders. Conclusion These findings showed that lifetime cocaine use is a potential predictor of conversion to BD in an MDD cohort. Further studies are needed to assess the possible underlying mechanisms linking exposure to cocaine with BD conversion.