Diagnostic validity of comorbid bipolar disorder and obsessive-compulsive disorder: a systematic review

Objective At least 50% of bipolar disorder (BD) patients have an additional diagnosis, one of the most difficult to manage being obsessive–compulsive disorder (OCD). Defining the nosology of BD‐OCD comorbidity has important clinical implications, given that treatments for OCD can worsen BD outcomes. Method A systematic review was conducted on: i) BD‐OCD comorbidity lifetime prevalence and ii) on standard diagnostic validators: phenomenology, course of illness, heredity, biological markers, and treatment response. Relevant papers published through March 30th 2013 were identified searching the electronic databases MEDLINE, Embase, PsycINFO, and the Cochrane Library. Results Sixty‐four articles met inclusion criteria. Lifetime comorbidity prevalence was 11–21% in BD patients and 6–10% in OCD patients. Compared to non‐comorbid subjects, BD‐OCD has a more episodic course of OC symptoms (up to 75% vs. 3%), typically with worsening during depression (78%) and improvement during mania/hypomania (64%), as well as a higher total mean number of depressive episodes (8.9 ± 4.2 vs. 4.1 ± 2.7) and perhaps more antidepressant‐induced mania/hypomania (39% vs. 9%). Conclusion In this first systematic review of BD‐OCD comorbidity, it appears that OC symptoms are usually secondary to BD, rather than representing a separate disease.