Comparison of ApoE-related brain connectivity differences in early MCI and normal aging populations: an fMRI study

In this study, we used resting-state functional magnetic resonance imaging (rs-fMRI) scans from subjects with early mild cognitive impairment (EMCI) and control subjects to study functional network connectivity. The scans were acquired by the Alzheimer's Disease Neuroimaging Initiative (ADNI). We used genetic data from the ADNI database to further subdivide the EMCI and control groups into genotype groups with or without the Apolipoprotein E allele e4 (APOE e4). Region of interest (ROI)-to-ROI resting-state functional connectivity was measured using Freesurfer and the Functional Connectivity Toolbox for Matlab (CONN). In our analysis, we compared whole-brain ROI connectivity strength and ROI-to-ROI functional network connectivity strength between EMCI, control and genotype subject groups. We found that the ROI network properties were disrupted in EMCI and APOE e4 carrier groups. Notably, we show that (1) EMCI disrupts functional connectivity strength in many important functionally-linked areas; (2) APOE e4 disrupts functional connectivity strength in similar areas to EMCI; and (3) the differences in functional connectivity between groups shows a multifactor contribution to functional network dysfunction along the trajectory leading to dementia.