Age-related changes of the corticospinal tract in the human brain A diffusion tensor imaging study

The corticospinal tract(CST) is one of the most important neural tracts for motor function in the human brain.Little is known about age-related changes of the CST.In this study,we tried to evaluate age-related changes of the CST using diffusion tensor imaging in 60 healthy subjects.The diffusion tensor imaging result revealed that the tract number and fractional anisotropy value were decreased,and the apparent diffusion coefficient(ADC) value was increased with aging.The distribution showed a semilog pattern for tract number,fractional anisotropy and ADC of the CST,and the pattern of each graph was near-linear.When compared with the diffusion tensor imaging parameters of subjects in the 20 s age group,tract number and fractional anisotropy values were significantly decreased in the 50 s-70 s age groups.Likewise,the ADC value was significantly higher in the 50 s-70 s age groups.The CST in the brain of normal subjects degenerated continuously from the 20 s to the 70 s,with a near-linear pattern,and degeneration of the CST began to manifest significantly in the subjects in their 50 s,compared with the subjects in their 20 s.