Fig 4. Age-related changes in T1W and T2W signal intensity in the white matter tracts of the genu, splenium, and left corticospinal tract. In the genu, T1W signal intensity was not significantly correlated with age in either the central (r² = 0.03823; P = .2461) or peripheral region (r² = 0.005794; P = .6543). T2W signal intensity significantly declined with age in both the central (r² = 0.09326; P = .0348) and peripheral regions (r² = 0.2891; P = .0001). A similar overall pattern is present in the left corticospinal tract. T1W signal intensity was not significantly correlated with age in either the central (r² = 0.02530; P = .3541) or peripheral region (r² = 0.005692, P = .6619) and T2W signal intensity decreases with age in both the central (r² = 0.5204, P < .0001.) and cortical peripheral (r² = 0.3975; P < .0001) regions. In the splenium, a different pattern is evident. T1W signal intensity decreases with age in the central (r² = 0.1207; P = .0352) but not the peripheral region (r² = 0.01349; P = .4937). T2W signal intensity significantly decreased with age in the peripheral region (r² = 0.1818; P = .0025), but not in the central region (r² = 0.01067; P = .4848).