The illusion of simplicity: the medical model revisited

Traditional medical models have been found to be linear, restrictive, and oversimplified. Only a truly biological model, encompassing evolutionary as well as molecular and cellular biology, can account for the complex origins, forms, and effects of disease, which are illustrated by a discussion of hepatitis B and slow virus disease. An updated biological model of disease takes into account predisposition to disease, the timing and route of infection, multiple disease forms, variable adaptive response, and the role of social and cultural factors and views disease as a failure of adaptation in one or more systems. Its application to psychiatry is shown in a discussion of stress, bereavement, and separation.