SEASONAL SYMPTOM VARIATION IN PATIENTS WITH CHRONIC FATIGUE - COMPARISON WITH MAJOR MOOD DISORDERS

The psychobiology of idiopathic fatigue has received renewed interest in the medical literature in recent years. In order to examine the rel ation between chronic, idiopathic fatigue and specific subtypes of dep ressive illness, we characterized the pattern and severity of seasonal symptom variation in 73 patients with chronic, idiopathic fatigue, co mpared to patients with major depression (n = 55), atypical depression (n = 35), and seasonal affective disorder (n = 16). Fifty of the fati gued subjects also met the specific Centers for Disease Control and Pr evention case criteria for chronic fatigue syndrome, though this defin ition was unable to discriminate a distinct subgroup of patients, base d on their seasonality scores alone. As a group, the fatigued subjects reported the lowest levels of symptom seasonality of any of the study groups. Further, even in those fatigued subjects with scores in the r ange of those seen in patients with seasonal affective disorder, seaso nality was not reported to be a subjectively distressing problem. Thes e findings lend support to the idea that although chronic fatigue shar es some clinical features with certain mood disorders, they are not th e same illnesses. These data are also consistent with the emerging vie w that chronic fatigue represents a heterogeneously determined clinica l condition.