Medical (fluoxetine) and psychological (cognitive-behavioural therapy) treatment for premenstrual dysphoric disorder: a study of treatment processes.

OBJECTIVES To investigate (i) the differential changes in premenstrual symptoms, mood, cognitions, and coping strategies during two treatments [cognitive-behavioural therapy (CBT) and fluoxetine] for premenstrual dysphoric disorder (PMDD) and (ii) the characteristics of those with good vs. poor outcome post treatment and at 1 year follow-up. METHODS Premenstrual symptoms, mood (Hospital Anxiety and Depression Scale, HADS), causal attributions, and use of cognitive and behavioural coping strategies were examined during 6 months of both treatments. The two treatment groups were then combined and divided on the basis of good vs. poor outcome posttreatment and at 1 year follow-up. Baseline measures were used to predict posttreatment outcome, and baseline and posttreatment measures were examined when attempting to predict outcome at 1 year follow-up. RESULTS Both treatments were equally effective at the end of 6 months (prospective daily diary measure). Fluoxetine treatment had a more rapid effect and greater impact upon anxiety symptoms, while CBT was associated with increased use of cognitive and behavioural coping strategies and a shift from a biomedical to a biopsychosocial causal attribution of premenstrual symptoms. Depressed mood at baseline assessment was associated with poorer response to both treatments, and learning active behavioural coping strategies was associated with a good outcome at 1 year follow-up. CONCLUSION These results provide evidence of differential treatment effects of fluoxetine and CBT for PMDD and offer information that will enhance clinical decision-making.