The Relationship of Personality Disorders to Treatment Outcome in Depressed Outpatients

Background: Many clinicians believe that depressed patients with comorbid personality disorder(s) may respond differently to standard treatments than patients with depression alone. Personality disorders appear to be common among patients with depression, suggesting potentially significant treatment implications for a large group of patients.

Method: Subjects with DSM-III-R major depression were recruited for a study looking at prediction of antidepressant response. All patients were assessed using the Structured Clinical Interviews for DSM-III-R Axis I and Axis II, as well as rated on the Hamilton Rating Scale for Depression and the Montgomery-Asberg Depression Rating Scale (MADRS). Patients were then randomly assigned to treatment with fluoxetine or nortriptyline and reassessed at 6 weeks. The major outcome measure was percentage reduction in MADRS scores.

Results: Of the 183 patients who completed the personality disorder assessment, 45% had at least 1 comorbid personality disorder. Subjects with comorbid personality disorders were slightly younger, more depressed at baseline, had poorer social adjustment, more general psychopathology, and more chronic depression. Despite these differences, the presence of a comorbid personality disorder did not adversely affect overall outcome at 6 weeks, but there was an interaction between having a comorbid personality disorder and drug type. The major effect was that patients with a cluster B personality disorder did relatively poorly on nortriptyline compared with fluoxetine treatment.

Conclusion: The finding that the presence of a comorbid personality disorder does not affect overall treatment response is similar to that reported by some recent studies. The finding that patients with cluster B personality disorders respond poorly to nortriptyline is also consistent with a small literature on borderline personality disorder.