Alterations in Resting-State Functional Connectivity Between the Hippocampus, Thalamus, Amygdala and the Whole Brain in Patients with Amnestic Mild Cognitive Impairment

Abstract

Abstract Background Amnestic mild cognitive impairment (aMCI) refers to a transitional stage between normal aging and Alzheimer's disease (AD). At present, numerous studies have reported that the functional connectivity between the hippocampus, thalamus, amygdala and other brain regions is abnormal in patients with MCI and AD. However, few studies have investigated hippocampal, thalamic, amygdalar and whole-brain functional connectivity abnormalities. Methods Here, we recruited 33 patients with amnestic mild cognitive impairment (aMCI) and 33 age- and sex-matched healthy controls (HCs) and chose the hippocampus, amygdala, and thalamus as regions of interest to explore the functional connectivity between the hippocampus, amygdala, thalamus and the whole brain in patients with aMCI. Results Using the hippocampus as region of interest, the whole brain functional connectivity analysis showed that the functional connectivity with the left precuneus, the right precuneus, and the parahippocampal gyrus was increased, and the functional connectivity with left anterior cingulate gyrus was reduced compared with the HC group. Using the thalamus as a region of interest, the whole-brain functional connectivity analysis showed that functional connectivity with the fusiform gyrus, left/right inferior occipital gyrus and left middle occipital gyrus was increased. Using the amygdala as a region of interest, whole-brain functional connectivity analysis showed reduced functional connectivity with the right frontal apex, the right central gyrus and left thalamus and the right supplementary motor area. Conclusions We found abnormal functional connectivity in patients with aMCI, indicating that it may provide a reliable imaging index for the early recognition and intervention of AD.