The association between Obsessive-Compulsive Disorder and Bipolar Disorder has been suggested since Morel (1860) who described obsessive-compulsive symptoms among bipolar patients. Pierre Janet (1898) created the concept of Psychasthénie, in which he included: obsessions and impulsions, most of anxious and phobic symptoms, some delusional states, some forms of periodic depression and episodic mood disorders. Other classic authors have mentioned this comorbidity.

According to more recent studies, the prevalence of OCD among patients diagnosed with Bipolar Disorder varies from 16 to 35%. On the other hand some obsessive patients seem to present a Cyclothymic OCD, pointing to a co-morbid Bipolar Disorder.

The authors present one case study of a 50-year-old Caucasian male with present diagnostic of Bipolar Disorder and previous history of Obsessive-Compulsive Disorder.

This comorbidity constitutes a diagnostic challenge with therapeutic implications. Sometimes the obsessive symptoms are underdiagnosed at the depressed patient delaying the adequate treatment with anti-obsessive agents. The bipolar OCD has deficient response to antidepressants and usually requires treatment with a mood stabilizer.