Microstructural differences in white matter tracts in Alzheimer’s disease, cerebrovascular disease, and Parkinson's disease

Motivation: Few studies have directly compared white matter tract damage across different dementia aetiologies. Goal(s): We aimed to characterize and compare microstructural damage within white matter tracts in three neurodegenerative disease cohorts. Approach: Tractography was performed on diffusion tensor images from 96 Alzheimer's, 107 cerebrovascular disease, and 117 Parkinson's patients to compare the microstructure of 39 tracts. Results: The Parkinson's cohort had higher fractional anisotropy and lower mean diffusivity, axial diffusivity, and radial diffusivity in various tracts compared to both the Alzheimer's and cerebrovascular disease cohorts. There were very few significant differences between the Alzheimer's and cerebrovascular disease cohorts. Impact: White matter tract microstructure is slightly more preserved in Parkinson's compared to Alzheimer's or cerebrovascular disease. These results reinforce the need for higher-quality, advanced diffusion imaging techniques to detect the more subtle white matter degeneration in Parkinson's disease patients.