Advances in psychiatric epidemiology: rates and risks for major depression.

Over the last decade there has been a marked increase in information on the epidemiology of psychiatric disorders, particularly major depression, in adults living in the community and in families. The ability to conduct large epidemiologic studies of psychiatric disorders is due to improvements in diagnostic precision and reliability in psychiatry and to the development of systematic methods for collecting information on signs and symptoms to make diagnoses. Results from a recently completed epidemiologic survey of psychiatric disorders in five urban communities in the United States and from several large-scale family genetic studies suggest that major depression is a highly prevalent disorder. It occurs in adults and children, and there is evidence for an increased rate in younger people. The average age of first onset is in young adulthood. Most depressions are untreated. The firm risk factors for major depression include being female; young (born after World War II); separated/divorced or in an unhappy marriage; and having a family history of major depression. There is a two-to-threefold increased risk for major depression if there is a family history of the disorder. The relevance of these findings to clinical practice and public health is discussed.