Association of Apolipoprotein E Gene Polymorphism With Cognitive Function of the Elderly Residents in a Rural Community

ABSTRACT

BACKGROUND: It is not clear whether polymorphism of the apolipoprotein E (ApoE) gene influences the cognition of community residents. The aim of this study was to establish the association between ApoE gene polymorphism and cognitive function in an elderly rural community in Korea. METHODS: A total of 388 subjects aged 65 and over were recruited. Demographic characteristics, past history of illness, and scores on the Korean version of the Mini Mental State Examination (K-MMSE), the Geriatric Depression Scale . Short Form (GDS-S), and the Korean version of Instrumental Activities of Daily Living (K-IADL) were evaluated. The lipid profile and ApoE genotype were sampled from 377 of the participants. RESULTS: Of the entire cohort, 75% had less than 6 years of education, and 30% were illiterate. The frequencies of the ApoE epsilon2, ApoE epsilon3, and ApoE epsilon4 alleles were 48 (6.6%), 372 (86.9%), and 49 (6.5%), respectively. The K-MMSE score was much lower in those with two ApoE epsilon3 alleles than in those with only one ( p=0.046). However, the numbers of ApoE epsilon2 alleles (p=0.976) and ApoE epsilon4 alleles (p=0.934) carried by the individual were not associated with K-MMSE score. Both K-IADL (p<0.001) and GDS-S (p<0.001) scores were significantly correlated with K-MMSE score. Grouping of the participants into three groups according to K-MMSE score (i.e., 0-17 , 18-24, and 25-30) also revealed that this score was correlated with K-IADL score (p<0001), GDS-S score (p<0.001), and the ApoE epsilon3 allele (p=0.035). CONCLUSIONS: These results suggest that the ApoE epsilon3 allele has a negative influence on cognitive function (K-MMSE) in this rural community. Surprisingly, we were unable to detect any relationship between the ApoE epsilon4 allele and cognitive function. There was a positive correlation between K-MMSE, K-IADL, and GDS-S scores.