Doctors annually treat between approximately four and eight million Americans for depression. Behavioral changes in depressed individuals are characterized by sadness, loneliness, and apathy. Other symptoms include fatigue, early morning insomnia, loss of appetite, and suicide attempts. Underlying depression may mask itself in physical symptoms, alcohol or drug addiction, and even hyperkinesis in children. The American Psychiatric Association classifies all depressions as either mild, moderate (neurotic), or severe (psychotic). Depression occurs at all ages, from infants to the elderly, and each age group appears to have its own set of depression-provoking situations. Studies indicate that depression may peak in adolescence, drop off between ages 20 and 35, and then slowly rise again. Both heredity and environment appear to play important roles in depression. Current theories suggest that depressive illness results from feelings of helplessness following a loss of self-esteem. Other theories concentrate on faulty thought processes; a person perceives situations incorrectly and this perception affects how he feels. Depressive illnesses respond well to current treatment methods including drug therapy, psychotherapy, milieu therapy, psychodrama, occupational therapy, and electroconvulsive therapy; however, the possibility of suicide must always be considered in cases of depression. (NRB)