Temperament, character and personality disorders as predictors of response to interpersonal psychotherapy and cognitive-behavioural therapy for depression.

BACKGROUND Interpersonal psychotherapy and cognitive-behavioural therapy are widely accepted as effective treatments for major depression. There is little evidence on how personality disorder or personality traits affect treatment response. AIMS To determine whether personality disorder or traits have an adverse impact on treatment response to interpersonal psychotherapy or cognitive-behavioural therapy in people receiving out-patient treatment for depression. METHOD The study was a randomised trial in a university-based clinical research unit for out-patients with depression. RESULTS Personality disorder did not adversely affect treatment response for patients with depression randomised to cognitive-behavioural therapy. Conversely, personality disorder did adversely affect treatment response for patients randomised to interpersonal psychotherapy. CONCLUSIONS Despite the two therapies having comparable efficacy in patients with depression, response to interpersonal psychotherapy (but not cognitive-behavioural therapy) is affected by personality traits. This could suggest the two therapies are indicated for different patients or that they work by different mechanisms.