Prevalence of premenstrual dysphoric disorder in female patients with seasonal affective disorder

Background: Both seasonal affective disorder/winter type (SAD) and premenstrual dysphoric disorder (PMDD) are cyclical disorders characterized by so-called atypical depressive symptoms. In the present study we compared the point prevalence rates of PMDD between a sample of premenopausal female patients suffering from SAD and healthy female controls. Methods: Forty-six female patients with SAD and 46 healthy controls were included in our study. All subjects underwent a semistructured clinical interview according to DSM IV criteria and completed the Seasonal Pattern Assessment Questionnaire. PMDD was diagnosed in a self-rating interview for PMDD according to DSM IV criteria. To verify the diagnosis of PMDD, all patients were followed up in stable summer remission using daily self-rating scales for two full menstrual cycles. Results: Patients with SAD fulfilled significantly more often the diagnostic criteria for PMDD than female healthy controls (46% vs. 2%, respectively; chi-square: P<0.001). Conclusions: These results provide preliminary evidence for a high point prevalence rate of PMDD in premenopausal females with SAD. Clinical implications: It would be worthwhile to investigate whether an additional diagnosis of PMDD has an impact on the clinical outcome and the response to bright light therapy in female patients with SAD.