Age-related regional patterns in cerebral microstructure revealed using mean apparent propagator (MAP) MRI

The relationship between brain microstructure and aging has been the subject of intense study. We used the mean apparent propagator (MAP) MRI framework, which is suitable to characterize diffusion in complex microstructure, to investigate age-related differences in a cohort of cognitively unimpaired participants, spanning a wide age range. In white matter, we established an opposing pattern of higher non-Gaussianity (NG) alongside lower propagator anisotropy (PA) among older adults. In gray matter, these two indices were consistent with one another, and exhibited regional pattern heterogeneity compared to other microstructural parameters. These results suggest that MAP-MRI provides otherwise inaccessible regional microstructural information.