Personality change after severe head injury.

Personality change is widely reported after head injury, but rarely investigated quantitatively. This Paper summarises recent quantitative studies concerned with the natural history of personality change after severe head injury; its nature; its prediction; and its consequences. Reports of personality change increase with increasing time after injury, and the changes reflect a variety of phenomena including changes in affect, behaviour, maturity, and responsibility. Although there is a relationship between injury severity and personality change, other features such as premorbid personality and lifestyle are important. A severe personality change has important functional consequences. Families become heavily burdened, and patients with severe personality change are very unlikely to return to work.