Effects of aging on brain volumes in healthy individuals across adulthood.

In this retrospective study, we analyzed the effects of age on brain volumes in healthy brains across adulthood. We investigated the correlations between brain volumes and age in the brains of 563 healthy individuals (age range: 20-86, 55% female) whose MRI scans and related information were drawn from the IXI database ( brain-development.org/ixi-dataset /). We conducted a regression analysis to assess the effect of age on whole-brain volumes as well as selected regional volumetric measures. The whole-brain analysis revealed a negative linear relationship between gray matter (GM) and age as well as nonlinear patterns of the relationship between age and the white matter (WM), cerebrospinal fluid (CSF), and the GM/WM ratio across adulthood. The regional volumetric analysis showed linear and non-linear age-related regional volumetric changes with aging. Our present findings contribute to the understanding of how structures in the human brain change over the adult years and will help address the pathological age-related neural changes in age-related neural disorders such as Parkinson disease and Alzheimer disease.