New methods in psychiatric epidemiology

Research on the epidemiology of mental disorders has now reached the stage where it is possible for comparisons to be cautiously made between population samples. This is made possible for the following reasons: recognition that the populations at risk, including their age composition and exclusions, must be clearly specified; the use of the standardized diagnostic criteria in international use (ICD-10 and DSM-IV); and standardized clinical assessments, such as the Schedule for Clinical Assessment in Neuropsychiatry, the Diagnostic Interview Schedule (DIS) or Composite International Diagnostic Interview (CIDI), including the automated CIDI-A, and for the elderly, the Geriatric Mental State Examination and the Canberra Interview for the Elderly. Some recommendations are made for future epidemiological studies, including these advances in methodology. Emphasis is given to the value of using continuous measures of symptoms, in addition to categorical diagnoses. In research on etiology, investigators should make every effort to test innovative hypotheses, particularly where these involve both biological and psychosocial variables.