Seasonal mood symptoms in bulimia nervosa and seasonal affective disorder.

Mood and appetite disturbances are commonly found in bulimia nervosa and seasonal affective disorder (SAD). To investigate seasonality of mood symptoms, we administered the Seasonal Pattern Assessment Questionnaire (SPAQ) to 38 consecutive bulimic patients, 38 age- and sex-matched SAD patients, and 25 age- and sex-matched normal controls. The SPAQ is a reliable, retrospective, self-rated questionnaire that assesses seasonal changes in mood, sleep, weight, and social activity. The SAD patients had significantly higher Global Seasonality Scores (GSS) than the bulimic patients, who had higher scores than the control group (F = 78.6, df = 2.98, P less than .0001). Forty-two percent of bulimics met case-finding SPAQ criteria for SAD, compared with none of the control group (chi 2 = 14.1, df = 1, P less than .0005). These data suggest that a significant number of unselected bulimic patients have seasonal mood symptoms as severe as that seen in SAD. We propose that a common neurobiologic abnormality, such as serotonergic dysfunction, may underlie the common symptoms found in bulimia and SAD.