Unveiling the Hidden Connections in Amnestic Mild Cognitive Impairment

Published on May 17, 2022

Imagine you’re solving a complex puzzle and you carefully examine each piece, searching for patterns and connections. That’s exactly what scientists did in this study to uncover the hidden links in the brains of patients with amnestic mild cognitive impairment (aMCI), a condition associated with a high risk of developing Alzheimer’s disease. Using advanced neuroimaging techniques, they combined structural and functional approaches to reveal the intricate workings of the brain in aMCI. They found that certain areas of the brain, like the right superior and middle frontal gyrus, showed decreased activity, while the left inferior frontal gyrus demonstrated both reduced gray matter volume and activity. Additionally, they discovered disrupted resting-state functional connectivity between key regions implicated in memory function. These findings shed light on the shared features of both structural and functional changes in aMCI and provide valuable insights into the underlying mechanisms of this condition and its relationship to Alzheimer’s disease.

Amnestic mild cognitive impairment (aMCI) is a clinical subtype of MCI, which is known to have a high risk of developing Alzheimer’s disease (AD). Although neuroimaging studies have reported brain abnormalities in patients with aMCI, concurrent structural and functional patterns in patients with aMCI were still unclear. In this study, we combined voxel-based morphometry (VBM), amplitude of low-frequency fluctuations (ALFFs), regional homogeneity (Reho), and resting-state functional connectivity (RSFC) approaches to explore concurrent structural and functional alterations in patients with aMCI. We found that, compared with healthy controls (HCs), both ALFF and Reho were decreased in the right superior frontal gyrus (SFG_R) and right middle frontal gyrus (MFG_R) of patients with aMCI, and both gray matter volume (GMV) and Reho were decreased in the left inferior frontal gyrus (IFG_L) of patients with aMCI. Furthermore, we took these overlapping clusters from VBM, ALFF, and Reho analyses as seed regions to analyze RSFC. We found that, compared with HCs, patients with aMCI had decreased RSFC between SFG_R and the right temporal lobe (subgyral) (TL_R), the MFG_R seed and left superior temporal gyrus (STG_L), left inferior parietal lobule (IPL_L), and right anterior cingulate cortex (ACC_R), the IFG_L seed and left precentral gyrus (PRG_L), left cingulate gyrus (CG_L), and IPL_L. These findings highlighted shared imaging features in structural and functional magnetic resonance imaging (MRI), suggesting that SFG_R, MFG_R, and IFG_L may play a major role in the pathophysiology of aMCI, which might be useful to better understand the underlying neural mechanisms of aMCI and AD.

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