CROSS-NATIONAL EPIDEMIOLOGY OF MAJOR DEPRESSION AND BIPOLAR DISORDER

Objective.-To estimate the rates and patterns of major depression and bipolar disorder based on cross-national epidemiologic surveys. Design and Setting.-Population-based epidemiologic studies using similar met hods from 10 countries: the United States, Canada, Puerto Rico, France , West Germany, Italy, Lebanon, Taiwan, Korea, and New Zealand. Partic ipants.-Approximately 38 000 community subjects. Outcome Measures.-Rat es, demographics, and age at onset of major depression and bipolar dis order. Symptom profiles, comorbidity, and marital status with major de pression. Results.-The lifetime rates for major depression vary widely across countries, ranging from 1.5 cases per 100 adults in the sample in Taiwan to 19.0 cases per 100 adults in Beirut. The annual rates ra nged from 0.8 cases per 100 adults in Taiwan to 5.8 cases per 100 adul ts in New Zealand. The mean age at onset shows less variation (range, 24.8-34.8 years). In every country, the rates of major depression were higher for women than men. By contrast, the lifetime rates of bipolar disorder are more consistent across countries (0.3/100 in Taiwan to 1 .5/100 in New Zealand); the sex ratios are nearly equal; and the age a t first onset is earlier (average, 6 years) than the onset of major de pression. Insomnia and loss of energy occurred in most persons with ma jor depression at each site. Persons with major depression were also a t increased risk for comorbidity with substance abuse and anxiety diso rders at all sites. Persons who were separated or divorced had signifi cantly higher rates of major depression than married persons in most o f the countries, and the risk was somewhat greater for divorced or sep arated men than women in most countries. Conclusions.-There are striki ng similarities across countries in patterns of major depression and o f bipolar disorder. The differences in rates for major depression acro ss countries suggest that cultural differences or different risk facto rs may affect the expression of the disorder.