• The brain metabolic pattern of patients with winter seasonal affective disorder with and without light treatment was determined by positron emission tomography. Compared with controls, patients with seasonal affective disorder with and without light treatment had globally lower metabolic rates, relatively lower superior medial frontal cortex rates, and somewhat higher basal ganglia rates. Patients receiving light treatment had a relatively higher rate in an occipital region of interest containing the primary visual cortex. Patients without light treatment had relatively higher metabolic rates in right parietal and medial orbitofrontal cortex and lower rates in the left parietal cortex. Patients not receiving light treatment had a hemispheric metabolic asymmetry (left greater than right) for the midprefrontal cortex located 67 mm above the canthomeatal line. The right side of this region, previously found reduced in manic-depressive illness and schizophrenia, was decreased primarily in patients with seasonal affective disorder with fewer atypical depressive symptoms. These "abnormal" prefrontal and parietal cortex regions appeared highly "coupled" in the patients with seasonal affective disorder.
Cohen RM, Gross M, Nordahl TE, Semple WE, Oren DA, Rosenthal N. Preliminary Data on the Metabolic Brain Pattern of Patients With Winter Seasonal Affective Disorder. Arch Gen Psychiatry. 1992;49(7):545-552. doi:10.1001/archpsyc.1992.01820070039006