REGIONAL CEREBRAL BLOOD-FLOW CHANGES AFTER LIGHT THERAPY IN SEASONAL AFFECTIVE-DISORDER

There is considerable evidence to indicate that depressive disorders m ay be associated with changes in regional cerebral blood flow (rCBF), and that successful treatment map reverse these changes. We studied pa tients with seasonal affective disorder (SAD) using Tc-99(m)-hexamethy lpropylene amine oxime (Tc-99(m)-HMPAO) single photon emission tomogra phy (SPET) to examine the effect of light therapy on rCBF. Ten depress ed patients (8 females, 2 males) with a mean (+/- S.D.) age of 33.5 +/ - 11.3 years underwent Tc-99(m)-HMPAO SPET studies before and after li ght therapy. The treatment response was evaluated using the Structured Interview Guide for the Hamilton Depression Rating Scale - Seasonal A ffective Disorders Version (SIGH-SAD). A patient was considered respon sive to light therapy if the post-treatment SIGH-SAD score was reduced by 60% or more in comparison to the pre-treatment score (responders, n = 5; non-responders, n = 5). Pre- and post-treatment SIGH-SAD scores and SPET data were compared in each patient. An improvement in depres sive symptoms after light therapy was associated with an increase in r CBF in the frontal and cingulate regions as well as the thalamus. Such changes were not seen in non-responsive subjects.