Abnormal global functional network connectivity and its relationship to medial temporal atrophy in patients with amnestic mild cognitive impairment

Abstract

BackgroundAmnestic mild cognitive impairment (aMCI), which is recently considered as a high risk status for developing Alzheimer’s disease (AD), manifests with gray matter atrophy and increased focal functional activity in the medial temporal lobe (MTL). However, the abnormalities of whole-brain functional network connectivity in aMCI and its relationship to medial temporal atrophy (MTA) remain unknown.MethodsIn this study, thirty-six aMCI patients and thirty-five healthy controls (HCs) were recruited. Neuropsychological assessments and MTA visual rating scaling were carried out on all participants. Furthermore, whole brain functional network was constructed at voxel level, and functional connectivity strength (FCS) was computed as the sum of the connections for each node to capture its global integrity. General linear model was used to analyze the FCS values differences between aMCI and HCs. Then, the regions showing significant FCS differences were adopted as the imaging markers for discriminative analysis. Finally, the relationship between FCS values and clinical cognitive scores was correlated in patients with aMCI.ResultsComparing to HCs, aMCI exhibited significant atrophy in the MTL, while higher FCS values within the bilateral MTL regions and orbitofrontal cortices. Notably, the right hippocampus had the highest classification power, with the area under receiver operating characteristics (ROC) curve (AUC) of 0.790 (confidence interval: 0.678, 0.901). Moreover, FCS values of the right hippocampus and the left temporal pole were positively correlated with the cognitive performance in aMCI.ConclusionThis study demonstrated significantly structural atrophy and raised global functional integrity in the MTL, suggesting simultaneous disruption and compensation in prodromal AD. Increased intrinsic functional connectivity in the MTL may have the potential to discriminate subjects with tendency to develop AD.

Management Based on Multimodal Brain Monitoring May Improve Functional Connectivity and Post-operative Neurocognition in Elderly Patients Undergoing Spinal Surgery

“…Although the diagnostic value of ALFF has been demonstrated for AD, subjective cognitive decline, and amnestic MCI (Yang et al, 2018;Zhuang et al, 2020), few studies have examined ALFF in relation to the development of PND. Decreasing ALFF values have been observed in the precuneus, anterior cingulate cortex, parahippocampal gyrus, and temporal lobe of patients with AD with disease progression (Liu et al, 2014;Sheng et al, 2017;Yang et al, 2018). We also observed changes in ALFF in some of these brain regions, although some of our findings diverged from those of other studies: we found that ALFF was decreased in the Hip of patients in Group C, whereas an increase in ALFF was reported in the left Hip of patients with AD (Liu et al, 2014;Yang et al, 2018).…”

Hippocampus Radiomic Biomarkers for the Diagnosis of Amnestic Mild Cognitive Impairment: A Machine Learning Method

“…A structural MRI study indicated that the texture of hippocampus might serve as a neuroimaging biomarker for detecting early cognitive impairment (Sørensen et al, 2015). Some MRI studies demonstrated that the altered functional connectivity and the altered volume differences exist between the right and left hippocampi of MCI and AD (Peter et al, 2017; Sheng et al, 2017). Some studies reveal that the left hippocampus has greater atrophy than the right one in AD patients (Li et al, 2016).…”

“…For example, structural brain MRI using voxel-based morphometry demonstrated hippocampal atrophy in AD and aMCI (Mcdonald et al, 2009; Fouquet et al, 2012). Some resting-state functional MRI studies have found abnormal functional connectivity between the hippocampus and other brain regions and in internal hippocampus in AD or MCI (Dennis and Thompson, 2014; de Flores et al, 2017; Sheng et al, 2017). In addition, diffusion tensor imaging studies indicated mean diffusivity abnormalities in the hippocampal region of patients with MCI (Fellgiebel et al, 2006; Mak et al, 2017).…”

Neuroimaging Advances in Preclinical Alzheimers disease

“…Neuroimaging Advances in Preclinical Alzheimer's disease with MCI had increased functional activities within medial temporal lobe in compensating for brain structural damages [41][42][43]. One latest research has also verified the consistent functional activation in hippocampus during the memory encoding task for amyloid-positive asymptomatic subjects [44].…”