December 2, 1992

The Changing Rate of Major DepressionCross-National Comparisons

Author Affiliations

College of Physicians and Surgeons, Columbia University, and New York State Psychiatric Institute, New York, NY; Department of Psychiatry, Washington University School of Medicine, St Louis, Mo; University of Connecticut School of Medicine, Farmington (data collected at University of California, Los Angeles); Department of Psychiatry, University of Alberta, Edmonton; Behavioral Sciences Research Institute, University of Puerto Rico, San Juan; Max Planck Institute of Psychiatry, Clinical Institute, Munich, Germany; Department of Neurology and Psychiatry, Florence University Medical School, Florence, Italy; Department of Psychiatry, Groupe Hospitalier Bichat-ClaudBernard, Paris, France; Institut National de la Santé et de la Recherche Médicale, Villejuif, France; St Joseph University, St Georges Hospital, and American University of Beirut, Lebanon; Departments of Community Health and General Practice and Psychiatry, Christchurch School of Medicine, Christchurch, New Zealand; Department of Psychiatry, National Taiwan University, College of Medicine, Taipei, Taiwan; New York Hospital—Cornell Medical Center, New York, NY; Department of Psychiatry, Brown University, Providence, RI; Abteilung für Psychiatrie, University of Mainz, Mainz, Germany
From the Cross-National Collaborative Group.

JAMA. 1992;268(21):3098-3105. doi:10.1001/jama.1992.03490210080039

Objective.  —To estimate temporal trends in the rates of major depression cross-nationally.

Design.  —Nine epidemiologic surveys and three family studies.

Setting and Participants.  —Approximately 39 000 subjects in population-based samples from nine epidemiologic surveys, and 4000 relatives from three family studies that were conducted independently but using similar methodology in the 1980s in North America, Puerto Rico, Western Europe, the Middle East, Asia, and the Pacific Rim.

Outcome Measures.  —Age at first onset of major depression by birth cohort and time period.

Results.  —There was an increase in the cumulative lifetime rates of major depression with each successively younger birth cohort at all sites with the exception of the Hispanic samples, in whom the rates in the older cohort (1915 through 1935) were approximately equal to those of the younger cohorts. However, results of fitting statistical models that separate period and cohort effects showed an overall increase in the rates of major depression over time over all countries, although the magnitude of the increase varied by country. The average relative risk of major depression between a particular cohort and the cohort born immediately before varied between 2.6 (95% confidence interval, 1.8 to 3.7) in Florence, Italy, and 1.3 (95% confidence interval, 1.2 to 1.4) in Christchurch, New Zealand. Short-term fluctuations in the rates of major depression during specific time periods and in specific cohorts also varied by country.

Conclusions.  —Cross-nationally, the more recent birth cohorts are at increased risk for major depression. There are, however, variations in the long- and short-term trends for major depression by country, which suggests that the rates in these countries may have been affected by differing historical, social, economic, or biological environmental events. The linking of demographic, epidemiologic, economic, and social indices by country to these changes may clarify environmental conditions that influence the rates of major depression.(JAMA. 1992;268:3098-3105)