SEASONAL AFFECTIVE-DISORDER

Seasonal affective disorder (SAD) is a form of recurrent depressive or bipolar disorder, with episodes that vary in severity. Seasonal patte rns of depressive episodes are common, but SAD seems to be less common than such patterns suggest. SAD was at first believed to be related t o abnormal melatonin metabolism, but later findings did not support th is hypothesis. Studies of brain serotonin function support the hypothe sis of disturbed activity. The short-allele polymorphism for serotonin transporter is more common in patients with SAD than in healthy peopl e. Atypical depressive symptoms commonly precede impaired functioning, and somatic symptoms are frequently the presenting complaint at visit s to family physicians, The best treatment regimens include 2500 Ix of artificial light exposure in the morning. When patients seem to have no response or to prefer another treatment, antidepressants should be considered.