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Updated: May 11, 2026
Diffusion Tensor Magnetic Resonance Imaging in the Analysis of Neurodegenerative Diseases
Published on: July 28, 2013
Gray matter microstructure from in-vivo diffusion MRI reflects post-mortem neuropathology severity and clinical
Zaki Alasmar1,2,3, Cécilia Tremblay1,2,4, Roqaie Moqadam1,5
1Cerebral Imaging Centre, Douglas Mental Health University Institute, Montréal, Québec, Canada, H4H 1R3.
Introduction:
Diffusion-weighted imaging derived mean diffusivity (MD) correlates with Alzheimer's disease biomarkers, yet its neuropathological correlates remain unclear.
Methods:
Diffusion-weighted imaging, postmortem neuropathology, and cognitive performance data were obtained from the National Alzheimer's Coordinating Center (N=97), Alzheimer's Disease Neuroimaging Initiative (N=21), and Arizona Study of Aging and Neurodegenerative Disorders (N=15). We examined MD associations with neuropathology, cognitive decline, and expression profiles of AD-implicated genes.
Results:
Results revealed two latent variables-one linked to amyloid/tau, the other to vascular pathology-explaining 70% and 16% of MD-pathology covariance, respectively. Higher MD correlated with worse cognitive performance, both cross-sectionally and up to 14 years prior to death. MD was regionally associated with Thal phase, neuritic plaque density, Braak stage (temporal/limbic), and infarcts (thalamus), and reflected gene expression patterns related to AD.
Discussion:
In vivo MD captures distinct AD-related pathologies across brain regions and relates to cognitive trajectories and gene expression.
Insights
Mean diffusivity (MD) from diffusion-weighted imaging reflects Alzheimer's disease (AD) brain changes and predicts cognitive decline. This in vivo measure links to amyloid, tau, and vascular pathologies, offering insights into disease progression.
Area of Science:
- Neuroimaging
- Neuropathology
- Genetics
Background:
- Diffusion-weighted imaging (DWI) derived mean diffusivity (MD) shows correlation with Alzheimer's disease (AD) biomarkers.
- However, the precise neuropathological underpinnings of MD in AD remain incompletely understood.
Purpose of the Study:
- To investigate the relationship between in vivo MD and postmortem neuropathological findings in Alzheimer's disease.
- To explore associations between MD, cognitive decline trajectories, and gene expression profiles.
Main Methods:
- Utilized data from multiple cohorts (N=133) including DWI, postmortem neuropathology, and cognitive performance.
- Examined correlations between MD, neuropathological markers (amyloid, tau, vascular pathology), and AD-implicated gene expression.
Main Results:
- Two major latent variables explained MD-pathology covariance: one linked to amyloid/tau (70%), the other to vascular pathology (16%).
- Higher MD correlated with worse cognitive performance, both cross-sectionally and longitudinally.
- Regional MD was associated with specific pathologies including Thal phase, plaque density, Braak stage, and infarcts, and reflected AD-related gene expression.
Conclusions:
- In vivo MD is a valuable neuroimaging marker that captures distinct Alzheimer's disease-related pathologies across brain regions.
- MD relates to cognitive trajectories and gene expression patterns, providing a comprehensive view of AD pathophysiology.
