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Updated: Jun 19, 2026
08:43
Application of Granger Causality Analysis of the Directed Functional Connection in Alzheimer's Disease and Mild Cognitive Impairment
Published on: August 7, 2017
Regional pattern of white matter microstructural changes in normal aging, MCI, and AD
D Y Lee1, E Fletcher, O Martinez
1Imaging of Dementia and Aging (IDeA) Laboratory, Department of Neurology and Center for Neuroscience, University of California at Davis, Davis, CA 95616, USA. selfpsy@snu.ac.kr
Neurology
|October 23, 2009
Summary
Alzheimer disease (AD) and vascular risk both damage white matter microstructure, impacting cognitive function. This damage varies by brain region and disease severity, affecting normal-appearing white matter differently than white matter hyperintensities.
Area of Science:
- Neuroimaging
- Neurology
- Gerontology
Background:
- Cognitive impairment, including mild cognitive impairment (MCI) and Alzheimer disease (AD), is associated with white matter (WM) microstructural changes.
- Distinguishing between degenerative and vascular contributions to WM injury is crucial for understanding disease progression.
Purpose of the Study:
- To compare regional white matter fractional anisotropy (FA) in cognitively normal (CN) individuals, MCI, and AD patients.
- To investigate the roles of normal-appearing white matter (NAWM) and white matter hyperintensities (WMH) in these differences.
- To determine the independent effects of degenerative (AD) and vascular processes on WM FA.
Main Methods:
- Diffusion tensor imaging (DTI) and vascular risk evaluation were performed on 47 AD patients, 73 MCI patients, and 95 CN subjects.
- Cerebral white matter was stratified into four regions (H1-H4) based on baseline FA levels from young healthy individuals to control for regional variability.
- FA was analyzed within NAWM and WMH, and across different FA strata.
Main Results:
- Patients with AD showed significantly lower FA than CN or MCI individuals in higher anisotropy strata (H1-H3), associated with long corticocortical fibers.
- Vascular risk independently affected FA in most strata (except H1) within NAWM.
- FA was significantly lower in WMH compared to NAWM across all strata, irrespective of diagnosis or vascular risk.
Conclusions:
- Both vascular factors and Alzheimer disease pathology contribute to white matter microstructural injury.
- These processes exhibit distinct, region-specific patterns of injury across the spectrum of cognitive function.
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