In the US, major depression is more common among whites than among African Americans or Mexican Americans, just the opposite is true of a lesser depressive disorder classified as dysthymia, researchers have found.

Dysthymia is defined as a chronic depressive mood disorder that afflicts sufferers on more days than not and for most of the day. Symptoms can include poor appetite or overeating, poor sleep or oversleeping, fatigue, low self-esteem, difficulties concentrating or making decisions, and feelings of hopelessness.

Using data from the National Health and Nutrition Examination Survey III, Dr. Stephanie A. Riolo, from the University of Michigan in Ann Arbor, and colleagues assessed racial disparities in rates of major depressive disorder and Dysthymia. Data from 8449 subjects between 15 and 40 years of age were included in the analysis.

According to a report in the American Journal of Public Health, the lifetime prevalence of major depressive disorder for whites was 10.4 percent, significantly higher than the 7.5 percent and 8.0 percent rates seen in African Americans and Mexican Americans, respectively.

On the other hand, corresponding prevalence figures for Dysthymia were 5.7 percent, 7.5 percent and 7.4 percent.

Poverty status was associated with major depression, but only among white subjects, the investigators found. Similarly, lack of education raised the risk of major depressive disorder, but only among Mexican Americans.

Lack of education was a significant risk factor for dysthymia. Attaining an educational level beyond middle school markedly cut the risk among white subjects. For the other ethnic groups, however, the drop in risk with each educational level was less pronounced and was modified by gender.

Although poverty and lack of education may partially explain the findings, the investigators note, “other cultural factors may have a mediating effect.”

SOURCE: American Journal of Public Health, June 2005.