ABSTRACT
No one really knows why some people get depressed-or fail to respond to antidepressant or psychotherapeutic treatment-but it is probably the result of a combination of factors. Historically, several nonbiological, psychoanalytically and cognitively based theories-such as aggression turned inward, object loss, loss of self-esteem, cognitive, learned helplessness, and negative reinforcement, among others [1,2]—have been widely used to explain major depression as well as most other mood disorders.
