A Norwegian psychiatric epidemiological study

Objective: This study reports results of a large-scale epidemiological inve stigation of the prevalence of mental disorder in Oslo. Method: A random sample of Oslo residents age 18-65 years was drawn from th e Norwegian National Population Register. A total of 2,066 subjects, 57.5% of the original sample, were interviewed with the Composite International D iagnostic Interview in 1944-1997. The mean age of the interviewed subjects was 39.3 years. Results: The 12-month prevalence of all mental disorders was 32.8%, and the lifetime prevalence was 52.4%. Alcohol abuse/dependence and major depressi on had the highest lifetime prevalence and 12-month prevalences. All mental disorders were more prevalent in women than in men, with the exception of alcohol and drug abuse/dependence. Severe psychopathology (e.g., three or m ore diagnoses) was found in 14%-15% of the respondents. The lifetime and 72 -month prevalences for all diagnostic categories except drug abuse/dependen ce were similar to those found in the United States Comorbidity Survey. Conclusions: Epidemiological data for Oslo show that the lifetime and 12-mo nth prevalences of mental disorder are quite high, with alcohol abuse/depen dence and major depression particularly frequent. The rates for women are h igher than those for men for all diagnostic categories, except for alcohol and drug abuse/dependence.