The origins of American psychiatric epidemiology.

Psychiatric epidemiology developed relatively late (as compared with epidemiology generally). Nineteenth century psychiatrists, although avid collectors of statistics, did not use such data in any systematic manner. The impetus for the creation of an epidemiology of mental illness came from the work of late nineteenth century social scientists concerned with understanding individual and social behavior and applying their findings to social problems. Initially they helped to create the modern census, which represented a radical faith that quantitative research, when merged with administrative rationality, could replace politics. During and after the 1920s, the demographic analysis of the institutionalized mentally ill population expanded sharply; by the late 1930s and 1940s psychiatric epidemiologists had begun to study the role of socioenvironmental variables and the incidence of mental illness in the community. Twentieth century psychiatric epidemiologists, however, faced a severe intellectual problem; their work rested on a descriptive rather than an etiological nosology. Consequently, the results of epidemiological studies in psychiatry often differed precisely because of variations in the design of studies and classification systems as well as the subjective observations of the investigators themselves. The ensuing disagreements among those involved in the epidemiologic study of mental illness were a natural consequence.