Comorbidity and Depression Treatment

Comorbidity is common among patients with major de-pression, but in most instances it may be of little rele-vance. Nonetheless, it is a complex issue because of its relation to treatment response, and few studies have attempted to address this. Most have examined comorbid-ity after the fact in secondary analyses. In this article, I focus on whether comorbidity influences depression treat-ment response among patients who are primarily diag-nosed as suffering from major depression. At least three comorbidities are believed to influence treatment re-sponse: medical, anxiety, and personality disorders. Whether studies find that these factors predict worse outcomes in patients with major depression appears to depend on the nature and severity of the medical illness, the study setting, and the study design. The best designed studies reported the least effects of these factors on treatment outcome. Clinically, this suggests that these factors should not be seen as impediments to treatment