Longitudinal changes in microstructural white matter metrics in Alzheimer's disease

Area of Science:

• Neuroimaging
• Neurodegenerative Diseases
• Biomarkers

Background:

• Alzheimer's disease (AD) is a progressive neurodegenerative disorder.
• Current AD research prioritizes pre-symptomatic biomarkers for early diagnosis.
• Existing MRI-based biomarker research predominantly examines grey matter, with limited focus on white matter.

Purpose of the Study:

• To investigate within-group microstructural white matter changes in AD patients and healthy controls over one year.
• To examine between-group microstructural differences in white matter between AD patients and healthy controls at baseline and one year.

Main Methods:

• Utilized longitudinal diffusion tensor imaging (DTI) data from the Alzheimer's Disease Neuroimaging Initiative 2 database.
• Employed longitudinal Tract-Based Spatial Statistics (TBSS) for within-group and between-group analyses.
• Assessed changes in fractional anisotropy (FA) and mean diffusivity (MD) as indicators of white matter microstructure.

Main Results:

• Both AD patients and controls showed widespread decreases in FA and increases in MD over one year.
• The hippocampal cingulum exhibited changes exclusive to the AD group.
• AD patients displayed significantly lower FA and higher MD in multiple white matter tracts compared to controls, including the corpus callosum, internal/external capsule, and various fasciculi.

Conclusions:

• White matter microstructure alterations are sensitive indicators and potential biomarkers for Alzheimer's disease.
• Further longitudinal studies incorporating both white and grey matter are recommended to assess clinical utility for AD diagnosis.