Prevalence and incidence of severe mental illness in the United States: an historical overview.

The nineteenth century witnessed growing alarm among professionals and the public in the United States and Europe that the number of people in mental hospitals was rapidly rising. Whether this growth was caused by an increase in the incidence or prevalence of mental illness or by other factors has been debated for over 150 years. Those who believe that mental illness did increase attribute the change mainly to a rise in alcoholism, functional psychoses, syphilis, and disorders related to senescence. The hypothesis that functional psychoses increased has generated the most debate and is the focus of the present article. Those who believe that mental illness did not increase attribute the growth in mental hospital populations to various other factors that influence hospitalization. This article presents an historical overview of this long and complex debate. It is a balanced presentation of the arguments for and against a rise in mental illness. Original data from U.S. censuses and national reporting of mental hospital statistics are incorporated.