Perspectives on the past and future of psychiatric epidemiology. The 1981 Rema Lapouse Lecture.

Two generations of epidemiological studies of the true prevalence of mental disorders have been conducted since the turn of the century. The first and smaller in number took place prior to World War II and was characterized by the use of records and key informants to define "cases." The second, utilizing the greatly expanded nomenclatures that followed World War II, were based for the most part on personal interviews with all subjects or samples there of in communities all over the world. In total, more than 80 different communities were studied by more than 60 different investigators or teams of investigators in these first and second generation studies. The legacy from these studies comes in two main parts: the first consists of methodological problems centering on the question of how to conceptualize and measure mental disorders independently of treatment status; the second is a set of consistent substantive findings about the amounts of various types of mental disorder, the proportions treated and untreated by members of the mental health professions, and the distribution of the disorders according to gender, rural vs urban location, and social class. Analyses of this legacy from first and second generation studies are presented with a view to developing informed speculations about what might be hoped for in the future, vastly different, third generation of studies in this field.