Q. Do certain ethnic groups have a higher risk of getting Alzheimer's disease?
A. Part of the problem in tackling questions of ethnicity and Alzheimer's disease, is that there are few research studies on the issue. In addition, those studies which have been done need to be replicated to see if the results are reliable and valid. However, a recent study suggests that different ethnic groups may have different genetic risks for developing AD.
A study in the March 11, 1998 issue of the Journal of the American Medical Association (Tang, et al.) investigated the incidence of Alzheimer's disease among 1,079 people living in northern Manhattan,New York. A similar number of nondemented elderly whites, African-Americans, and Hispanics were followed annually for up to five years. The study focused on the genetic evidence for a particular gene, the apolipoprotein E4 (APOE-4) allele, which has been associated as an increased risk factor for acquiring AD. Persons of all three ethnic backgrounds with at least one APOE-4 gene were equally likely to develop AD. However, in the absence of any APOE-4 genes, African-Americans and Hispanics were two to four times more likely than whites to develop AD by age 90. This increase in risk was not related to the presence of cardiovascular disease, a family history of AD-like dementia, or to differences in education. The study concludes that in addition to APOE, some previously unidentified genes or other risk factors may be contributing to the development of AD in African-Americans and Hispanics.
It is important to keep in mind that research studies such as this one are preliminary and need replication to confirm their findings. However, they do raise interesting questions about the relative importance of genetic versus environmental factors in the development of AD. It does appear that the risk for getting AD differs across ethnic groups, but further research to determine how and why these differences occur is needed.
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