The impact of comorbid dysthymic disorder on outcome in personality disorders.

Objective: The goal of our study was to investigate the impact of dysthymic disorder (DD), a form of chronic depression, on naturalistic outcome in individuals with personality disorders (PDs).

Method: The Collaborative Longitudinal Personality Disorders Study is a cohort initially including 573 subjects with 4 targeted PDs (borderline, avoidant, schizotypal, and obsessive-compulsive) and 95 subjects with major depression but no PD. At baseline, 115 subjects were diagnosed with coexisting DD, of whom 109 (94.8%) were PD subjects. Regression analyses were performed to predict 3 classes of broad clinical outcome after 2 years of prospective follow-up. We hypothesized that DD diagnosis at baseline would be associated with worse outcome on (1) persistence of a PD diagnosis, (2) impairment in psychosocial functioning (as measured by the Longitudinal Interval Follow-up Evaluation), and (3) crisis-related treatment utilization.

Results: Baseline DD diagnosis was associated with persistence of PD diagnosis at 2 years, particularly for borderline and avoidant PDs. It was associated with worse outcome on global social adjustment, life satisfaction, recreation, and friendships, but not employment or relationship with spouse. Contrary to expectation, DD did not increase suicide attempts, emergency room visits, or psychiatric hospitalizations.

Conclusions: Comorbidity of DD is associated with persistence of PD diagnosis and with worse outcome on many, but not all, measures of psychosocial functioning.