FOLLOW-UP-STUDY OF SEASONAL AFFECTIVE-DISORDER IN SWITZERLAND

Of 39 diagnosed Seasonal Affective Disorder (SAD) patients who were in terviewed 2-5 years after participation in a light therapy trial, 10 c ontinued to have recurrent major depressive episodes in winter, and 17 manifested sub-syndromal SAD (2 patients also had recurrent brief dep ression, seasonal type). 8 patients had recovered, and 4 had shifted i n symptomatology. Thus, over a number of years, the clinical diagnosis changed for the better in 64% of the patients, suggesting that SAD is not a prodromal form of a more chronic major affective disorder, and that light therapy (and perhaps also light-oriented behaviour) reduced the incidence and depth of subsequent depressive episodes. Further ev idence for this was the large reduction in use of conventional antidep ressant drugs (from 17 to 1) during the follow-up period. Diagnosis of SAD was stable and reliable.