Structural and functional brain changes in the default mode network in subtypes of amnestic mild cognitive impairment
Xin Li1, Miao Cao1, Junying Zhang1
1State Key Laboratory of Cognitive Neuroscience and Learning & IDG/McGovern Institute for Brain Research, Beijing Normal University, Beijing, PR China.
Background:
Various amnestic mild cognitive impairment (aMCI) subtypes have been identified as single domain (SD) or multiple domain (MD), with differential probabilities of progression to Alzheimer disease (AD). Detecting the differences in the alterations in gray matter (GM) and intrinsic brain activity between the subtypes of aMCI help to understand their pathophysiological mechanisms and was conducive to construct such potential biomarkers to monitor the progression of aMCI.
Methods:
In all, 22 normal controls (NCs), 18 patients with SD-aMCI, and 17 patients with MD-aMCI participated in the study. The amplitude of low-frequency fluctuations (ALFFs) during rest represented intrinsic brain activity. Voxel-based morphometry analysis was used to measure the GM volume.
Results:
The MD-aMCI showed reduced GM in hippocampus (Hip), parahippocampal gyrus (PHG), and other regions than SD-aMCI. The SD-aMCI had reduced GM only in Hip and PHG than in NC. The MD-aMCI showed decreased ALFF in posterior cingulate cortex (PCC) and precuneus and increased ALFF in anterior cingulate cortex (ACC), PHG, and Hip compared with both SD-aMCI and NC. However, no ALFF difference was found between SD-aMCI and NC. Neuropsychological measures were correlated with ALFF in PCC and ACC only in the MD-aMCI.
Conclusions:
Patients with MD-aMCI displayed more severe GM atrophy and ALFF changes than patients with SD-aMCI. The results suggested that aMCI is heterogeneous and that MD-aMCI may be a prodromal stage which is more close to AD.
Insights
Multiple domain amnestic mild cognitive impairment (aMCI) shows greater gray matter loss and altered brain activity than single domain aMCI. MD-aMCI may represent an earlier stage of Alzheimer disease (AD).
Area of Science:
- Neuroimaging
- Cognitive Neuroscience
- Neurology
Background:
- Amnestic mild cognitive impairment (aMCI) has subtypes: single domain (SD) and multiple domain (MD).
- These subtypes have different progression rates to Alzheimer disease (AD).
- Understanding GM and brain activity differences aids in identifying biomarkers for aMCI progression.
Purpose of the Study:
- To investigate differences in gray matter (GM) volume and intrinsic brain activity between SD-aMCI and MD-aMCI.
- To explore the potential of these differences as biomarkers for aMCI subtypes and progression.
Main Methods:
- Compared 22 normal controls (NCs), 18 SD-aMCI patients, and 17 MD-aMCI patients.
- Measured intrinsic brain activity using amplitude of low-frequency fluctuations (ALFFs).
- Assessed gray matter (GM) volume using voxel-based morphometry.
Main Results:
- MD-aMCI patients exhibited reduced GM in the hippocampus (Hip) and parahippocampal gyrus (PHG) compared to SD-aMCI.
- SD-aMCI patients showed GM reduction only in Hip and PHG relative to NC.
- MD-aMCI patients displayed decreased ALFF in the posterior cingulate cortex (PCC) and precuneus, and increased ALFF in the anterior cingulate cortex (ACC), PHG, and Hip compared to both SD-aMCI and NC.
Conclusions:
- MD-aMCI demonstrates more significant GM atrophy and ALFF alterations than SD-aMCI.
- aMCI is a heterogeneous condition.
- MD-aMCI may be a prodromal stage of AD, indicating closer proximity to the disease.
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