The history of psychiatric epidemiology can be divided into three phases. In the first phase, which originated in German psychiatry, it was assumed that psychiatric illnesses were mainly hereditary in etiology, and research was focused on hospitalized patients with severe mental illness. After World War II, psychiatric epidemiology was strongly influenced by sociological and social-anthropological thinking, especially in the United States. Many of the studies that were carried out in this second phase—the most famous of which are the Midtown Manhattan study (1) and the Stirling County (Canada) study of Leighton and colleagues (2)—did not focus on psychiatric diagnoses but on “psychiatric impairment.”
During the 1970s psychiatric epidemiology entered a new phase. The study by Weissman and Myers (3, 4), which developed from the Midtown Manhattan study, was the first American epidemiological study with a random sample of households and the first to use a structured diagnostic instrument (the Schedule for Affective Disorders and Schizophrenia—Lifetime Version). This was followed by the U.S. Epidemiologic Catchment Area (ECA) study (5, 6). In connection with the ECA study, a comprehensive structured interview, the National Institute of Mental Health Diagnostic Interview Schedule (DIS), was developed; this instrument could be administered by trained interviewers who were not necessarily psychiatrists or psychologists (7). The ECA study reports described the psychiatric illness picture in the United States in the early 1980s. The results showed that at one time or another 32% of adult Americans had experienced a diagnosable DSM-III psychiatric illness and that 20% had a psychiatric illness at the time of the study. Of great interest was the higher prevalence of psychopathology in younger compared with older respondents, an apparent cohort effect.