Personality pathology and treatment outcome in major depression: a review

A longstanding belief among many clinicians is that patients with depression and comorbid personality pathology have a worse response to standard depression treatment. This presents potentially significant treatment implications, since personality pathology in depressed patients appears to be common.

PsycINFO and MEDLINE were systematically searched for studies relating personality to treatment outcome. Over 50 studies were obtained and grouped according to the method used to assess personality pathology.

High neuroticism scores generally predicted worse outcome, especially over long-term follow-up. Tridimensional Personality Questionnaire scores did not have a consistent relationship to treatment outcome despite some promising initial findings. Most studies involved patients with comorbid personality disorders; these studies produced conflicting results. Other measures of personality pathology produced an array of findings ranging from a moderately worse outcome to no difference.

Whether or not personality pathology significantly worsens outcome in patients with major depression appears to depend on study design, since the rate of personality pathology varies markedly depending on how it is measured. In addition, depressed patients with personality pathology appear less likely to receive adequate treatment in uncontrolled studies. Finally, studies rarely control for depression characteristics (e.g., chronicity, severity) that may influence outcome and be related to personality pathology. Overall, the best-designed studies reported the least effect of personality pathology on depression treatment outcome. Clinically, this suggests that comorbid personality pathology should not be seen as an impediment to good treatment response.