Posted by Annapaola Prestia Laboratory of Epidemiology Neuroimaging and Telemedicine, IRCCS Centro San Giovanni di Dio FBF, The National Centre for Research and Care of Alzheimer’s and Mental Diseases, Brescia, Italy

Diffusion tensor Imaging (DTI) is a magnetic resonance imaging technique that provides a sensitive measure of change in the microstructure of white matter integrity. Previous studies suggested that age related microstructural alterations in white matter differ among regions, while sex effects and age-by-sex interactions effect on global or regional white matter integrity still remain unclear. This recent study has investigated age-related changes, sex differences, and age-by-sex interactions in white matter integrity across the whole brain in 857 healthy subjects (mean age = 56.1 ± 9.9 years; age range = 24.9-84.8 years). All subjects underwent DTI to examine the effects of age and sex on white matter. Results suggested that age-related changes in white matter integrity were more strongly associated with myelin sheath degeneration than with axonal degeneration. One of the new findings of the present study is that, in specific regions resistant to age-related degeneration (e.g. the splenium of the corpus callosum), the number of remyelinated axons might increase with age. Results also suggest that there are sex differences in white matter integrity in some regions, but there are no sex differences, neither an age-by-sex interaction in the aging process of the white matter. The study suggests a lack of sex difference in the aging process of white matter and an arising of theme in white matter integrity during its maturational process.