According to the results of a National Institutes of Health (NIH) study, reported in the December issue of the Archives of General Psychiatry, Mexican Americans and non-Hispanic Whites born in the United States have a higher risk for developing psychiatric disorders than their foreign-born counterparts who have immigrated to the United States.
The psychiatric disorders included alcohol and drug use disorders, major depression, dysthymia, mania, hypomania, panic disorder, social and specific phobia, and general anxiety disorder.
Based on the 2001-2002 National Epidemiologic Survey on Alcohol and Related Conditions (NESARC), the analysis is the first to consider immigration status in conjunction with psychiatric morbidity in each of four comparison groups: U.S.-born Mexican Americans, Mexican immigrants to the United States, U.S.-born non-Hispanic Whites, and non-Hispanic White immigrants to the United States. Earlier studies compared psychiatric disorder rates among U.S.- and foreign-born Mexican Americans to either rates for U.S.-born non-Hispanic Whites or rates for the entire U.S. population, thereby confounding immigration status and ethnicity.
"The remarkable pattern seen in these results defies explanation based on current knowledge," according to George Kunos, M.D., Ph.D., Scientific Director, Division of Intramural Biological and Clinical Research at the National Institute on Alcohol Abuse and Alcoholism (NIAAA), the NIH institute that conducted the study. "Additional careful research is required to understand the influences of individual and environmental factors in the causes of psychiatric disorders."
"As often occurs, our epidemiologists-researchers who study conditions and behaviors across large population groups-pose new and intriguing questions for researchers in other disciplines," he said. "Although it may be some time before scientists fully understand the causes of these disorders, service providers and policy makers have immediate use for the results."
Lead author Bridget Grant, Ph.D., Chief of the Laboratory of Biometry and Epidemiology in NIAAA's intramural research program, and her colleagues found that non-Hispanic Whites' lifetime rate of experiencing a psychiatric disorder (51.2 percent) was far greater overall than that for all Mexican Americans (36.7 percent). Psychiatric disorders were more prevalent among U.S.-born survey participants (47.6 percent among Mexican Americans and 52.5 percent among non-Hispanic Whites) than among their foreign-born counterparts (28.5 percent and 32.3 percent, respectively). Lifetime rates of alcohol use disorder and specific mood and anxiety disorder among U.S.-born Mexican Americans and non-Hispanic Whites were nearly twice those of their foreign-born counterparts. Drug use disorder rates among U.S.-born non-Hispanic Whites were more than twice those of their foreign-born counterparts, whereas the corresponding rates among U.S.-born Mexican Americans (12 percent) were eight times those of Mexican Americans born outside the United States (1.7 percent).