The Effect of Apolipoprotein E ε4 Genotype on the Medial Temporal Lobe Atrophy in Cognitively Impaired Patients With Amyloid Deposition: 2 Years Longitudinal Magnetic Resonance Imaging Study

ABSTRACT

Objective@#Apolipoprotein E (APOE) genotype is associated with risk of Alzheimer’s disease (AD), but the association ofAPOE ε4 allele with longitudinal medial temporal lobe atrophy (MTA) has been controversial. This study aims to evaluate the effect of APOE genotype on longitudinal MTA over a 2-year period in cognitively impaired patients with amyloid deposition. @*Methods@#This retrospective longitudinal study included 65 cognitively impaired subjects with amyloid deposition (subjective memory impairment, mild cognitive impairment, and mild AD). Participants were divided into carriers (n=27) and non-carriers (n=38) of the ε4 allele. The main outcome is longitudinal reduction of medial temporal lobe (hippocampus, entorhinal cortex, and parahippocampal gyrus) over 2 years. Analysis of covariance was conducted to compare the differences in longitudinal MTA between groups, controlling for covariates. @*Results@#At baseline, hippocampal volume was 4.6% smaller (6.38±1.13 vs. 6.69±0.83, p=0.026) and entorhinal thickness was6.4% thinner (3.51±0.57 vs. 3.75±0.52, p=0.033) in APOE ε4 carriers than non-carriers. Furthermore, APOE ε4 carriers had significantly 72% greater longitudinal hippocampal atrophy compared to non-carriers (-0.43±0.30 vs. -0.25±0.31, p=0.041). @*Conclusion@#Our findings of baseline or longitudinal MTA in APOE ε4 carriers suggest that APOE ε4 genotype may contrib-ute to underlying pathophysiology of medial temporal lobe in AD.