Explanatory style change during cognitive therapy for unipolar depression.

We administered the Attributional Style Questionnaire to 39 unipolar depressed patients at the beginning and end of cognitive therapy and at one-year follow-up, and we administered it to 12 bipolar patients during a depressed episode. A pessimistic explanatory style for bad events correlated with severity of depression for unipolars at cognitive therapy intake (r = .56, p < .0002), termination (r = .57, p < .0008), and one-year follow-up (r = .64, p < .0005) and among the bipolars (r = .63, p < .03). Explanatory style and depressive symptoms significantly improved by the end of cognitive therapy and remained improved at one-year follow-up. For the unipolars in cognitive therapy, explanatory style change from intake to termination correlated with change in depressive symptoms from intake to termination (r = .65, p < .0001). These results suggest that explanatory style may be one of the mechanisms of change for unipolar depressive patients undergoing cognitive therapy.