Relationship among neuroimaging indices of cerebral health during normal aging.

Sensitive measures of brain aging show great promise for gauging factors that affect aging and degenerative processes, such as risk genes or therapy. Here we examined age-related trends for three indices of cerebral health: gyral gray matter (GM) thickness, dilation of sulcal spaces with CSF, and the volume of T2-hyperintense white matter (HWM) lesions. The study involved 31 healthy adults age 57-82 years old. Measurements of average GM thickness, average sulcal span and HWM volume were performed using high-resolution 3D T1- and T2-weighted brain MR images. Age-related trends for the three cerebral health indices were consistent with previously published work though the analysis of their covariance led to a previously unreported relationship. Simultaneous multiple regression found that dilation of cortical sulci were primarily (t = 2.59, P < 0.01) related to the increases in HWM volume and secondarily related (t = -2.51, P < 0.01) to the reductions of the cortical GM thickness. The are-corrected correlation between reduction in GM thickness and increases in HWM volume, was not significant (P = 0.34). These findings are of interest in designing quantitative measures of brain aging for monitoring individual patients and in large-scale clinical trials.