The Association of APOE e4 Genotype With Cognition, Brain Volume, Glucose Metabolism, and Amyloid Deposition in AD

Objective: The purpose of this study is to investigate the association of the apolipoprotein E (APOE) e4 genotype with cognition, brain volume, glucose metabolism, and amyloid deposition in patients with Alzheimer disease (AD). Methods: This is cross-sectional study of 69 subjects with AD. All subjects were divided into carriers and non-carriers of the e4 allele. Forty APOE e4 carriers and 29 APOE e4 non-carriers underwent neuropsychological, structural magnetic resonance imaging, [18F]fluorodeoxyglucose positron emission tomography scans (PET) and [18F]florbetaben amyloid PET. Analysis of covariance was conducted to compare the differences on cognition, brain volume, glucose metabolism and amyloid deposition between APOE e4 carriers and non-carriers after controlling demographics. Results: APOE e4 carriers had 50% lower scores of Seoul Verbal Learning Test (delayed recall) compared to non-carriers (0.88±1.65 vs. 1.76±1.75, p<0.05). However, APOE e4 carriers performed better on other cognitive tests than non-carriers (Korean version of Boston Naming Test [11.04±2.55 vs. 9.66±2.82, p<0.05], Rey Complex Figure Test [25.73±8.56 vs. 20.15±10.82, p<0.05], and Stroop test [color response] [48.28±26.33 vs. 31.56±27.03, p<0.05]). APOE e4 carriers had slightly smaller hippocampal volume than non-carriers (3.09±0.38 vs. 3.32±0.38, p<0.05), but greater total brain cortical thickness (1.45±1.55 vs. 1.37±1.24, p<0.05). Amyloid deposition did not differ significantly between APOE e4 carriers and non-carriers, and no significant difference in glucose metabolism was found between groups. Conclusion: We found that APOE e4 genotype is associated with cognition, brain volume in AD, suggesting that APOE e4 genotype could play an important role in the underlying pathogenesis of AD.