Personality disorder comorbidity with major depression and response to fluoxetine treatment.

The relationship between depression and comorbid personality disorders is still poorly understood. The aims of this study were to examine differences in depression severity between depressed outpatients with and without comorbid personality disorders, to determine the effect of a fixed dose of fluoxetine on personality disorders, and to assess the predictive value of personality disorder diagnoses at baseline with regard to response to fluoxetine. Eighty-three outpatients with major depressive disorder (MDD) were assessed with a self-rating scale, the Personality Diagnostic Questionnaire-Revised (PDQ-R), before and after 8 weeks of treatment with fluoxetine 20 mg/day. The presence of a cluster B diagnosis before treatment predicted positive outcome as measured by the change in score on the modified 17-item Hamilton Rating Scale for Depression (HAM-D-17*). Following treatment, we found significant reductions in the frequency of most individual personality disorder diagnoses and total PDQ-R score. While patients no longer meeting criteria for cluster B personality disorders after treatment had similar reductions in depressive symptoms compared to those maintaining the diagnoses, subjects no longer meeting criteria for cluster A and cluster C diagnoses after treatment exhibited significantly greater decreases in depression severity than those who maintained the diagnoses. Overall, these results suggest that fluoxetine may be beneficial in the treatment of certain personality disorder traits in patients with MDD.