Aberrant Amplitude of Low-Frequency Fluctuation and Degree Centrality within the Default Mode Network in Patients with Vascular Mild Cognitive Impairment.

Haoyuan Li,Qi Yang,Xiuqin Jia,Xuejia Jia,Yingying Li

doi:10.3390/brainsci11111534

Abstract

This study aimed to investigate whole-brain spontaneous activities changes in patients with vascular mild cognitive impairment (VaMCI), and to evaluate the relationships between these brain alterations and their neuropsychological assessments. Thirty-one patients with VaMCI and thirty-one healthy controls (HCs) underwent structural MRI and resting-state functional MRI (rs-fMRI) and neuropsychological assessments. The functional alterations were determined by the amplitude of low-frequency fluctuation (ALFF) and degree centrality (DC). The gray matter volume (GMV) changes were analyzed using voxel-based morphometry (VBM). Linear regression analysis was used to evaluate the relationships between the structural and functional changes of brain regions and neuropsychological assessments. The VaMCI group had significantly lower scores in the Montreal Cognitive Assessment (MoCA), and higher scores on the Hamilton Anxiety Rating Scale (HAMA) and Hamilton Depression Rating Scale (HAMD). Compared to the HCs, the VaMCI group exhibited GM atrophy in the right precentral gyrus (PreCG) and right inferior temporal gyrus (ITG). VaMCI patients further exhibited significantly decreased brain activity within the default mode network (DMN), including the bilateral precuneus (PCu), angular gyrus (AG), and medial frontal gyrus (medFG). Linear regression analysis revealed that the decreased ALFF was independently associated with lower MoCA scores, and the GM atrophy was independently associated with higher HAMD scores. The current finding suggested that aberrant spontaneous brain activity in the DMN might subserve as a potential biomarker of VaMCI, which may highlight the underlying mechanism of cognitive decline in cerebral small vessel disease.

Highlights

Vascular mild cognitive impairment (VaMCI) is the early stage of vascular dementia (VaD), considered to be the most critical subtype of vascular disease due to cerebral small vessel disease (CSVD) [1]
The current finding suggested that aberrant spontaneous brain activity in the default mode network (DMN) might subserve as a potential biomarker of vascular mild cognitive impairment (VaMCI), which may highlight the underlying mechanism of cognitive decline in cerebral small vessel disease
Compared to the healthy controls (HCs) group, the VaMCI group showed a significant amplitude of low-frequency fluctuation (ALFF) decrease in the DMN, including the right precuneus (PCu), right angular gyrus (AG), right medial frontal gyrus, and left PCu (Table 2, Figures 1A and 2A), which remained after controlling for the nuisance variables of age, gender, education years, gray matter volume (GMV), and Hamilton Depression Rating Scale (HAMD)

Summary

Introduction

Vascular mild cognitive impairment (VaMCI) is the early stage of vascular dementia (VaD), considered to be the most critical subtype of vascular disease due to cerebral small vessel disease (CSVD) [1]. Even though several research studies have examined the neural mechanisms of CSVD and vascular cognitive impairment (VCI) during the last decade, the definitive conclusion of the neuropathological mechanism in VaMCI remains undetermined. More advanced than traditional MRI methods that are used to diagnose pathological changes in the late stage of brain vascular disease, amplitude low-frequency fluctuation (ALFF) is a kind of non-invasive resting-state functional MRI (rs-fMRI) technique, measuring the spontaneous total power of the BOLD signal, reflecting regional spontaneous neuronal activity in an early stage of the disease [3]. Altered ALFF values in brain regions have been identified predominantly in the default mode network (DMN) in VaMCI [4,5,6]

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