The seasonality of bipolar affective disorder: Comparison with a primary care sample using the Seasonal Pattern Assessment Questionnaire

Background: In contrast with recurrent unipolar depression, relatively little is known about the seasonality of depressive episodes in bipolar affective disorder (BAD). Method: We compared responses on the Seasonal Pattern Assessment Questionnaire (SPAQ) between a cohort of 183 patients with BAD and a large sample of patients in primary care (N = 4746). Comparisons were adjusted for age and gender. Results: 27% of the BAD patients fulfilled SPAQ criteria for Seasonal Affective Disorder (SAD. This gave an adjusted odds ratio of 3.73 (95% confidence intervals 2.64 to 5.27) in comparison with the rate among the primary care samples. Global seasonality scores were significantly higher among BAD patients (adjusted mean difference 1.73, 95% CI 0.97 to 2.49, p < 0.001). Limitations: The SPAQ was originally designed as a screening instrument rather than as a case-finding instrument. Conclusions: Vigilance for seasonal symptom recurrence in BAD may be important with regard to management and relapse prevention. (C) 2011 Elsevier B.V. All rights reserved.