Effects of Parkinson’s Disease on Mechanical and Microstructural Properties of the Brain

Magnetic Resonance Elastography (MRE) is a method capable of mapping the brain’s mechanical properties, however, the microstructural mechanisms responsible for these biomechanical properties remain largely unknown. For this reason, the present study utilized multidimensional diffusion-MRI (MD-dMRI), apart from MRE, to extract microstructural parameters for a cohort of Parkinson’s disease (PD) patients and healthy controls. Significant softening effects in the temporal and occipital lobes in PD were associated with an increase in mean diffusivity, whereas other microstructural properties, e.g. microscopic FA (µFA), largely remained unchanged. Across most regions, stiffness declined with age, which was correlated with a decrease in μFA and an increase in MD. We hypothesize that age softening effects mostly can be explained by neuronal atrophy, whereas PD effects involve additional mechanisms.