The psychobiology of idiopathic fatigue has received renewed
interest in the medical literature in recent years. In order
to examine the relation between chronic, idiopathic fatigue
and specific subtypes of depressive illness, we characterized
the pattern and severity of seasonal symptom variation in 73
patients with chronic, idiopathic fatigue, compared to
patients with major depression (n = 55), atypical depression
(n = 35), and seasonal affective disorder (n = 16) Fifty of
the fatigued subjects also met the specific Centers for
Disease Control and Prevention case criteria for chronic
fatigue syndrome, though this definition was unable to
discriminate a distinct subgroup of patients, based 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
range of those seen in patients with seasonal affective
disorder, seasonality was not reported to be a subjectively
distressing problem. These findings lend support to the idea
that although chronic fatigue shares some clinical features
with certain mood disorders, they are not the same illnesses.
These data are also consistent with the emerging view that
chronic fatigue represents a heterogeneously determined
Zubieta JK, Engleberg NC, Yargic LI, Pande AC, Demitrack MA