Longitudinal DTI Changes are Associated with Centiloids in Adults with Down Syndrome: an Alzheimer’s Study

Motivation: Diffusion-weighted MRI (dMRI) characterizes brain microstructure and has been used to study neurodegeneration in Alzheimer's Disease (AD). Since individuals with Down syndrome (DS) have a higher risk for early-onset AD, longitudinal dMRI may help track disease progression alongside amyloid-PET biomarkers. Goal(s): To study longitudinal diffusion tensor imaging (DTI) parameter relationships with amyloid-PET-derived Centiloids (CL) in DS. Approach: Tract-based spatial statistics and permutation-based linear models were used to identify regions significantly associated with longitudinal changes in DTI and CL. Results: Changes in DTI axial, mean, and radial diffusivities were significantly, directly associated with CL in regions like the longitudinal fasciculi and corpus callosum. Impact: Widespread bilateral regions showed direct significant diffusivity changes with CL changes. This suggests that changing white matter microstructure over time correlates with higher Aβ burden in adults with DS, indicating potential neurodegeneration and DTI as a means to assess it.