Figure 2.

(A,B) These plots are from Ge et al. (2002) and reflect different trajectories of white matter (WM) and gray matter (GM) over the life-span. The percent of GM volume total brain (TBV) volume declines with age whereas the percentage of WM to TBV shows and increase followed by decline later in life. Note that the age at which an individual is injured occurs not in a static brain, but rather in a brain that has age-dependent changes occurring simultaneously with the age when injury occurs. Reproduced with permission from The American Society of Neuroradiology.