Comorbidity in bipolar affective disorder

Abstract

What are the consequences of comorbidity in bipolar disorders? Two aspects deserve further consideration. First, comorbidity may delineate subtypes. Bipolar disorder and OCD together might be another type of disorder than each alone. Secondly, several studies have indicated that, when a patient suffers from more than one psychiatric disorder, treatment becomes more difficult and the course is more unfavourable (Sharma et al. 1995, Shwartz et al. 1996, Vogel and Huguelet 1997). However, is this also true for bipolar disorders? Recent studies, for example the NCS (Kessler 1999), have found that during their lifetime virtually all bipolar patients suffer from an additional psychiatric disorder. This casts some doubt on the relevance of such “lifetime comorbidity”. Can it actually worsen course and treatment response, when suffering from such a comorbid disorder seems to be the rule for patients with bipolar disorders? Furthermore, hardly any prospective studies have compared the course of comorbid and non-comorbid bipolar patients. Therefore, and due to the chronicity of bipolar disorders, comorbidity in bipolar disorder has to be assessed in a more complex way. In addition to the mere — categorical — diagnosis of a second disorder, its course, duration, severity and consequences must be assessed dimensionally. Truly multidimensional or multiaxial diagnostic strategies have to be developed further.