Apolipoprotein E polymorphism and cognitive impairment in a bi-ethnic community-dwelling elderly sample

The epsilon 4 (epsilon 4) and epsilon 2 (epsilon 2) alleles of the apolipoprotein gene (APOE) located on chromosome 19 have been associated with increased and decreased risk for Alzheimer disease (AD) in older adults, respectively. However, there is a dearth of studies examining the relation of APOE polymorphism with cognitive functioning among community-dwelling ethnic minority elderly. This study examined the risk for cognitive impairment associated with the APOE epsilon 4 and epsilon 2 alleles in a community-based cohort of non-Hispanic white (NHW; N = 739) and white Hispanics (WH; N=321). All patients were recruited consecutively from a memory-screening program and evaluated using standardized assessment procedures. Cognitive impairment was classified according to an age and education adjusted Folstein Mini-Mental State Exam (MMSAdj) score of less than 24. The results indicated the APOE epsilon 4 allele was associated with increased risk for cognitive dysfunction in NHW and WH after controlling for the effects of age, education, and gender. This risk was generally observed to be dose-dependent, with greater risk among epsilon 4 homozygotes in relation to epsilon 4 heterozygotes. The epsilon 2 allele of APOE did not confer decreased risk for cognitive impairment among NHW and WH. This study supports the relation of APOE polymorphism to cognitive dysfunction among two ethnic populations residing in the community.