Interaction Effects of Apolipoprotein E ε 4 and Cognitive Status on the Functional Connectivity within Default Mode Network in Individuals at Risk of Cognitive Impairments

Abstract

BackgroundDisturbance of intrinsic brain networks is often associated with APOE{varepsilon} 4 allele and cognitive dysfunction. However, little is known about the functional connectivity strength (FCS) within default mode network (DMN).\n\nObjectiveWe aimed to examine the independent effects APOE{varepsilon} 4 and cognitive status and the interaction effect on the functional connectivity within DMN.\n\nMethodsResting-state functional MRI was conducted for sixty-five senior adults who had normal cognition or cognitive decline with or without APOE{varepsilon} 4. Regions within DMN include mPFC, IPL, LTC, hippocampus and PCC. The absolute values of correlation coefficient between DMN regions were employed as the measures of FCS for quantifying the functional connectivity.\n\nResultsMain effect of APOE{varepsilon} 4 was found on the FCS of bilateral PCC (F = 6.133, p = 0.016), while the main effect of cognitive status was found on the FCS of left IPL and right mPFC (F = 4.585, p = 0.036). Interaction effect was found in the FCS of right mPFC and left LTC (F = 4.698, p = 0.034), right hippocampus and left LTC (F = 7.673, p = 0.008), left PCC and left LTC (F = 6.719, p = 0.012), right IPL and right LTC (F = 4.516, p = 0.038).\n\nConclusionsAPOE{varepsilon} 4 carriers with cognitive impairment denote a preclinical status characterized by aberrant inter-hemispheric FC within DMN. The network-level connectivity may be useful in the evaluation of the individuals at risk for developing AD and affiliate network-guided brain stimulation.