Clinical research is largely focused on depressive comorbidity in obsessive-compulsive disorder (OCD). However in practice, treating resistant or severe OCD sufferes revealed many cases who seem to have an authentic OCD with a hidden co morbid bipolar disorder.

To explore mood co morbidity, a sample of 33 OCD patients were administered structured self-rating questionnaires for major depression, hypomania and mania (DSM-IV criteria), and self-rated Angst's checklist of hypomania and cyclothymic temperament.

The rate of bipolar co morbidity in OCD was notable; 18% of the patients were BPI. Furthermore, the hypomania checklist of Angst showed that 39% had a cut-off score of 10. Analysis of the self-rated questionnaire for cyclothymic temperament showed that 52% scored 10.

Our data extend previous research on « OCD-bipolar comorbidity » as a highly prevalent and largely under-recognised and untreated class of OCD patients.