Epidemiology and natural history of schizophrenia.

The present review explores the descriptive epidemiology of schizophrenia. Risk factors and correlates are divided into three groups based on whether the available evidence is consistent and strong, consistent and potentially strong, or inconsistent. The paper then considers epidemiologic studies of the course of illness, including a description of findings from the Suffolk County Mental Health Project. Given renewed attention to the need for preventive interventions for individuals at high risk for developing a psychotic illness, epidemiologic values have become more and more central to the conduct of clinical research.