Almost everyone remembers when the research about Type A personalities was made public. It showed that men who were controlling, workaholic, and intense are more likely than others to suffer from heart disease and other stress-related illness. In the October 27, 1997 issue of Archives of Internal Medicine, a top medical journal, a report by Duke University research team filled in an important piece of previously missing information about Type A personalities. The team's question was, "What specific personality characteristic causes physical illness?" The answer it found: Anger. The Duke University study showed that cognitive/behavioral stress reduction sessions lowered the level of both anger and anxiety in patients with chronic heart problems, and that their physical improvement was related specifically to a reduction in their anger.
Futhermore, while it is generally agreed that holding anger in causes stress and physical illness, recent research shows that people who express anger often actually experience more physical symptoms and illness than those who hold their anger in.
As a cognitive/behaviorist, I do not subscribe to the Freudian definition of depression as "anger turned inward." However, I do believe that anger can be psychologically debilitating. People often see themselves as a being strongest and most assertive when they are angry. Actually, the opposite is true.