Differences in resting-state brain networks and gray matter between APOE e2 and APOE e4 carriers in non-dementia elderly

Background: Apolipoprotein E (APOE) e2 and APOE e4 are the most distinct alleles among the three APOE alleles, both structurally and functionally. However, differences in cognition, brain function, and brain structure between the two alleles have not been comprehensively reported in the literature, especially in non-demented elderly individuals. Methods: A neuropsychological test battery was used to evaluate the differences in cognitive performance in five cognitive domains. Independent component analysis (ICA) and voxel-based morphometry (VBM) were used separately to analyze resting-state functional magnetic resonance imaging (rs-fMRI) data and the structure MRI data between the two groups. Finally, correlations between differential brain regions and neuropsychological tests were calculated.Results: APOE e2 carriers had better cognitive performance in general cognitive, memory, attention, and executive function than APOE e4 carriers (all p < 0.05). In ICA analyses of rs-fMRI data, the difference in the resting-state functional connectivity (rsFC) between two groups is shown in 7 brain networks. In addition, VBM analyses of the T1-weighted image revealed that APOE e2 carriers had a larger thalamus and right postcentral gyrus volume and a smaller bilateral putamen volume than APOE e4 carriers. Finally, differences in brain function and structure may be might be the reason that APOE e2 carriers are better than APOE e4 carriers in cognitive performance.Conclusion: These findings suggest that there are significant differences in brain function and structure between APOE e2 carriers and APOE e4 carriers, and these significant differences are closely related to their cognitive performance.