Age-related changes of cerebral white and grey matter structures from childhood to adulthood using voxel-based morphometry

Objectives: Voxel-based morphometry (VBM) is an objective technique for characterising regional cerebral volume and tissue concentration differences in structural magnetic resonance images of the brain. In order to identify age- and sex-related differences, volumes of grey matter (GM), white matter (WM), and their substructures were studied in childhood, adolescence and young adulthood. Material and Methods: High resolution 3D-FLASH scans were obtained from 115 normal subjects (49 males, 66 females) from 0.5 to 30 years of age. VBM was carried out using Statistical Parametric Mapping (SPM2) software. Results: Relative to brain size, overall GM volume decreased non-linearly over this age range, whereas overall relative WM volume increased. Most rapid changes occurred in early childhood. The total volumes of both GM and WM increased non-linearly over this age range, with clearly stronger increased of WM than GM, resulting in an increase of the white-to-grey-matter ratio. In addition to these overall changes, regionally specific changes were observed. Sex differences were found to be more prominent after puberty with females having more cortical GM volume and males having bigger subcortical GM structures. Age-related regional changes of GM and WM volume were observed in various areas, some brain structures were found to diminish in size and others to increase at the same developmental stage. Conclusions: It appears likely that these changes reflect the functional development of the human brain, including both progressive (cell proliferation, arborisation, myelination) and regressive phenomena (apoptosis, synaptic and axonal pruning). The reported regionally dependent developmental and gender differences may be important to take into account when functional or structural changes are being investigated in healthy persons as well as in patients. Outlook: From these results it can be concluded that VBM is a powerful tool to quantify and localise changes in cerebral development and atrophy of GM and WM.