CHANGES IN REGIONAL CEREBRAL BLOOD-FLOW FOLLOWING LIGHT TREATMENT FORSEASONAL AFFECTIVE-DISORDER - RESPONDERS VERSUS NONRESPONDERS

Background: Several brain imaging studies of antidepressant pharmacolo gic treatment utilizing single photon emission computed tomography (SP ECT) have reported a normalization of deficits in cerebral bloodflow ( CBF) associated with recovery; other studies report no change, or a re duction in CBF following successful treatment. There have been no publ ished SPECT studies of seasonal affective disorder (SAD) assessing res ponse to light treatment in relation to changes in regional CBF (rCBF) , In this study, we sought to test the hypothesis that increases in rC BF would be observed in SAD patients who responded to light treatment. Methods: Ten depressed patients with SAD underwent functional brain i maging studies with Tc-99m-hexamethylpropyleneamine oxime SPECT before and after light treatment. Results: Relative increases in rCBF were o bserved in all brain regions compared to cerebellum in treatment respo nders, whereas nonresponders showed no change or decreases in rCBF rel ative to cerebellum. Significant differences in mean percentage change in rCBF between responders (n = 5) and nonresponders (n = 5) were det ected in frontal and cingulate cortex, and thalamus. Conclusions: Thes e findings provide preliminary support for the hypothesis that an incr ease in rCBF is associated with recovery from depression in SAD. (C) 1 997 Society of Biological Psychiatry.