Comorbid Bipolar Disorder and Obsessive-Compulsive Disorder: An Old Debate Renewed

Apparent comorbidity between bipolar disorder (BD) and anxiety disorders is a common condition in psychiatry with higher prevalence rates for generalised anxiety disorder, social phobia, panic disorder. 1 Overlapping clinical criteria for many diagnoses, especially mood and anxiety disorders, produced by the Diagnostic and Statistical Manual of Mental Disorders (DSM) might lay behind these high prevalence rates. 2 Using DSM, it is unclear whether concomitant diagnoses actually reflect the presence of distinct clinical entities or refer to multiple manifestations of a single clinical entity. With regard to anxiety disorders, one of the most difficult additional psychiatric diagnosis to manage in BD patients is obsessive-compulsive disorder (OCD). 3,4 In our recent meta-analysis, the pooled prevalence of OCD in BD was 17.0%, which was comparable to the results reported by the pooled prevalence of BD in OCD (18.35%). 5 In line with previous studies , 6 OCD prevalence rate was higher among BD children and adolescents (24.2%, compared to 13.5% in adults). The co-occurrence of symptoms of BD and OCD was noted 150 years ago by Morel, 7 but the topic is insufficiently studied and the relationship between BD and OCD remains unclear. In agreement with Kraepelin' s thought a psychiatric diagnosis is best established by its longitudinal course of illness, the evidence so far supports the view that, especially among patients with a primary diagnosis of BD, the majority of comor-bid OCD cases appeared to be related to mood episodes. 8 OC symptoms in comorbid patients appeared more often-and sometimes exclusively-during depressive episodes, and co-morbid BD and OCD cycled together, with OC symptoms often remitting during manic/hypomanic episodes. Therefore, only a substantial minority of comorbid BD-OCD may represent " true " OCD independent of BD with OC symptoms that improve or worsen during mood episodes without being related to these. These findings are in line with Feinstein's definition of co-morbidity, as " any distinct additional entity that has existed or may occur during the clinical course of a patient who has the index disease under study ". 2 " True " OCD comorbid with BD would represent the random co-occurrence of two independent diseases, estimated by multiplication of prevalence rates, which are about 1% for each condition, and producing a very low expected true comorbidity of 0.1% in the general population. The treatment of BD-OCD patients remains a great challenge , since the gold standard for one disease (serotonin reup-take inhibitors …