The relationship of cardiovascular risk factors to Alzheimer disease in Choctaw Indians.

OBJECTIVES: To test the hypothesis that cardiovascular risk factors (CRFs) influence predisposition to and the clinical course of Alzheimer disease (AD), the authors compared Choctaw Indians, a group with known high CRF with white persons with AD. In addition to CRF history, the authors investigated the frequency of apolipoprotein E4 (apoE4) genotype andplasma homocysteine (HC) levels.

METHOD: The authors compared 39 Choctaw Indians with AD and 39 Choctaw Indians without AD to 39 white persons with AD with all groups similar in age. CRF history included diabetes, hypertension, high cholesterol or hypolipidemic agent use, or myocardial infarction. The authors also compared plasma HC concentration and apoE4 allele frequency.

RESULTS: Choctaw persons with AD differed significantly from white persons with AD in history of hypertension, diabetes, and in HC values but not from Indians without AD. There was a significantly lower apoE4 allele frequency in Choctaw Indian AD than white persons with AD, and both AD groups had an affected first degree relative significantly more often than Indian controls. There was no relationship between the number of CRF and age at onset among Indians or whites, whereas HC concentration was associated with significantly earlier age of onset for Choctaw Indians but not for whites.

CONCLUSIONS: This small study suggests that in Choctaw Indians modifiable risk factors may play more of a role in disease pathogenesis than in whites and that nonmodifiable risk factors such as apoE4 may play less of a role.