Inter-regional gray matter correlation changes in normal aging

The human brain undergoes many age-related changes, such as the atrophy of brain volume, the thinner of cortical thickness, the loose of white matter and so on. Here we aimed to explore whether the covariance existed among the regional gray matter volume with aging. 169 brain magnetic resonance images (MRI) of healthy people (54 males and 115 females, 18 to 92 years) were selected from OASIS database. Firstly, we computed each regional gray matter volume using atlas-based registration method, and then we investigated the correlations with age between any two regions. We found that all 90 gray matter regions in whole brain decreased with age. In 4005 (90*89/2) pairs connections, 54 pairs were significantly (p<60;0.005) related with age. And in which, 24 pairs belonged to the regular connections between the left and right hemispheres. In other 30 pairs, 9 long-range connections between fronto-occipital, fronto-parietal and temporal-parietal regions were found to be impaired with age. We concluded that brain shrinkage was widespread and showed different rates in different regions. The volume of the frontal gyrus showed the fastest reduction. The covariations between inter-regional gray matter volumes may be related to various reduction rates of different regions.