Affective disorder is characterized by maladaptive changes in mood, attitudes, energy level, and physical status. These changes constitute the basic dimensions of depression. Depression results from a combination of genetic and experiential factors. There are sex differences and age differences with regard to depression, and there is a high correlation of depression between mothers and their children. Cognitive, learned helplessness, and behavioral theories have been proposed to explain the role of loss in depression. The role of loss in causing depression helps to account for the rapid increase in the frequency of affective disorders throughout adolescence. The normal developmental process presents teenagers with many real losses and threats to their sense of adequacy. Younger adolescents rarely display traditional adult symptoms of depression. Depressed adolescents may have problem behavior which they act out through temper tantrums, running away, stealing, truancy, and other rebellious or antisocial acts. By the age of 15 or 16, adolescents may exhibit depression through drug abuse, sexual promiscuity, alienation, or suicidal behavior. Studies show that children do not outgrow depression. Three forms of treatment are commonly used to treat depressed adolescents: psychotherapy, environmental manipulation, and drug therapy. Although only about five percent of all adolescents are diagnosed as depressed, the incidence of depression in adolescence probably greatly exceeds this level. (NB)