Seasonal patterns of bulimia nervosa

OBJECTIVE: The aim of this research was to determine whether a seasonal pattern to symptoms of bulimia nervosa could be identified. METHOD: In study 1, seasonal patterns of binge-purge frequency and mood were compared between 31 patients with bulimia nervosa and 31 age-matched normal comparison subjects, using a modified (to include binge and purge items) version of the Seasonal Pattern Assessment Questionnaire. Study 2 involved a cross-sectional examination of binge and purge frequency and of depressive symptoms in 197 patients with bulimia nervosa assessed at various months of the year over a 4-year period. RESULTS: In both the retrospective and cross-sectional studies, binge behavior was found to be highly associated with photoperiod. According to the modified Seasonal Pattern Assessment Questionnaire, purging behavior and mood also varied seasonally among patients with bulimia nervosa. However, purging behavior and severity of depression did not appear to be related to photoperiod in the cross-sectional study. The rate of seasonal affective disorder (syndromal and subsyndromal) defined by the Seasonal Pattern Assessment Questionnaire was higher among the bulimic group than the comparison subjects, but not as high as has been reported for depression in bulimia nervosa. CONCLUSIONS: The results strongly support the interpretation that symptoms of bulimia nervosa primarily associated with food intake patterns are influenced by seasonal variation, and this effect may be mediated by light availability.