Apolipoprotein E epsilon4, Alzheimer\u27s disease, and cognitive performance in elderly Mexican Mestizos

Objectives: To determine the relationship between apolipoprotein E (APOE) epsilon4 and Alzheimer\u27s disease (AD) in the Mexican Mestizo population, as well as its effects on the cognitive profile of AD and elderly Mestizos without dementia. Design: Cross-sectional analysis of a cohort study. Setting: Evaluations were conducted at the geriatrics clinic of an academic medical hospital in Mexico City. Participants: Forty-nine elderly subjects with AD and 141 controls selected from a representative sample of Mexican Mestizos aged 65 to 96 who participated in the Prevalence Survey of Dementia in the Mexico City Elderly Population cohort. Measurements: All subjects underwent APOE genotypification and a comprehensive clinical and neuropsychological evaluation. Results: There were no significant differences in epsilon3 and epsilon4 frequencies between the subjects with and without AD and a tendency toward higher epsilon4 and lower epsilon3 allele frequencies in subjects aged 75 and older. No association was found between APOE epsilon4 and the presence of AD. The age-, sex-, and education-adjusted risk for AD associated with at least one epsilon4 allele was 1.01 (95% confidence interval=0.45-2.23). Performance on a long-term visual memory test was significantly worse in APOE epsilon4 carriers than in APOE epsilon3 carriers only in the group with AD. Conclusion: APOE epsilon4 did not increase the risk for AD in this Mexican Mestizo elderly urban population sample, although the presence of this allele seems to modify its clinical expression