Alterations in intra- A nd interregional intrinsic brain connectivity are differentially associated with memory performance in amnestic mild cognitive impairment

Background: Previous research has separated spatial patterns of intra- A nd interregional intrinsic brain connectivity, as evaluated by regional homogeneity (ReHo) and functional connectivity (FC), respectively, in prodromal Alzheimer's disease (AD). Moreover, the intra- A nd interregional intrinsic brain connectivities have been demonstrated to have a significant relationship with each other. Objective: To explore FCs from brain regions which display a difference in ReHo between an amnestic mild cognitive impairment (aMCI) group and healthy controls (HC) and to examine the relationship of intra- A nd interregional intrinsic brain connectivity to cognitive function in both groups. Methods: Thirty-four subjects with aMCI and 38 HC underwent 3T MRI scanning and a battery of neuropsychological tests. Results: The aMCI group exhibited significantly higher ReHo in the left putamen and lower ReHo in the left inferior temporal gyrus than the HC. Furthermore, both groups showed a distinctive functional connectivity pattern seeded from 2 regions of interest which exhibited significant ReHo differences between the groups. In the HC group, only ReHo exhibited significant associations with memory performance, but in the aMCI group, only FC seeded from the left inferior temporal gyrus showed significant correlations with memory performance. Conclusions: By approaching both intra- A nd interregional intrinsic brain activities in the early stages of AD, the findings of this research provide insights into the early pathogenesis of AD as related to memory performance.