Investigations of the prevalence of psychiatric disorders

More than thirty studies of the prevalence of psychiatric disorders have been reported from Western countries in the last thirty years. Significant methodological advances have occurred, including sophistication of sampling techniques, improvements in caseness definitions and identification of cases, and clear definitions and specification of rules for diagnosis. The introduction of standardized diagnostic instruments for use by trained lay interviewers is expected to facilitate studies of psychiatric epidemiology. The methods used in each of the studies are briefly described.