Previous studies have demonstrated that Alzheimer’s disease (AD) and amnestic mild cognitive
impairment (aMCI) exhibited anatomical and functional abnormalities in the anterior cingulate
cortex (ACC) and accumulating evidence supported the hypothesis that changes in the ACC predict
the progression from aMCI to AD. In this study, we aimed to explore how the two functional and
structural heterogeneous sub-regions of ACC, namely the dorsal ACC (dACC) and the ventral ACC (vACC), changed in
aMCI and whether the structural connectivity affects the functional connectivity between the two ACC subregions. To investigate
this hypothesis, we studied resting-state fMRI and DTI images in a group of 24 aMCIs and 29 healthy controls.
The dACC exhibited a significantly increased functional connectivity in the Salience Network (SN) and a decreased functional
connectivity with the vACC in aMCI. The DTI results showed that the bilateral cingulum fibers were the most
damaged tracts in aMCI and that the fractional anisotrophy of the left anterior cingulum was significantly correlated with
the functional connectivity between the two ACC sub-regions. In conclusion, this study revealed the pathological changes
in the intrinsic functional connectivity of the ACC within SN, as well as the connectivity between the dACC and vACC in
aMCI. Our study also revealed that disrupted white matter integrity of the anterior regions of the cingulum was associated
with the alterations in subregional connectivity in the ACC.
Keywords: Amnestic mild cognitive impairment, anterior cingulate cortex, cingulum, diffusion tensor imaging, functional connectivity.
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