Apolipoprotein E epsilon4, Alzheimer's disease, and cognitive performance in elderly Mexican Mestizos

OBJECTIVES: To determine the relationship between apolipoprotein E (APOE) ɛ4 and Alzheimer's 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 ɛ3 and ɛ4 frequencies between the subjects with and without AD and a tendency toward higher ɛ4 and lower ɛ3 allele frequencies in subjects aged 75 and older. No association was found between APOE ɛ4 and the presence of AD. The age-, sex-, and education-adjusted risk for AD associated with at least one ɛ4 allele was 1.01 (95% confidence interval=0.45–2.23). Performance on a long-term visual memory test was significantly worse in APOE ɛ4 carriers than in APOE ɛ3 carriers only in the group with AD.
CONCLUSION: APOE ɛ4 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.