Regional changes of cortical mean diffusivities with aging after correction of partial volume effects

► Unbiased and comprehensive cortical mean diffusivities (MD) were quantified. ► Cortical MD profiles of young, elderly normal and Alzheimer (AD) were established. ► Cortical thinning in aging and AD brains caused bias of high cortical MD. ► Differences of unbiased cortical MD among young, old and AD group were delineated. ► A novel approach has been developed for measuring unbiased cortical MD.