Fractional anisotropy of water diffusion in cerebral white matter across the lifespan

Skeletonized, average FA values are shown on the population average FA image. WM-tract labels for eleven major tract are taken from John-Hopkins DTI WM atlas. The average FA values were calculated for the following tracts: CR (corona radiata), SLF (superior longitudinal fasciculus), Cingulate, EC (external capsule), IC (internal capsule), FO (fronto-occipital), CST (cortico-spinal), SS (sagittal striatum) and the Genu, Body and Splenium of Corpus Callosum.

Average FA values (●) stratified in 5 year intervals and age-related quadratic (solid curve, FA=0.52+22×10⁻⁴×age−0.30×10⁻⁴×age², r=0.49, p<1×10⁻²⁴) and linear maturation (dashed line, FA=0.51+14.1×10⁻⁴×age, r=0.33, p=10⁻⁸) and decline (dotted line, FA=0.59−14.3×10−⁴×age, r=0.57, p=1×10⁻¹⁶) trends for average FA. Age-of-peak (AOP)=32.1±5.9 years.

FA values for Corona Radiata (■) and Cortical-Spinal tract (▵) stratified in 5-year intervals. Age-related quadratic (thin curve, FA=0.46+15.6×10⁻⁴×age−0.27×10⁻⁴×age², r=0.58, p<1×10⁻²⁴) and linear maturation (dashed line, FA=0.46+4.6×10⁻⁴×age, r=0.1, p=0.8) and decline (dotted line, FA=0.51−13.3×10⁻⁴×age, r=0.64, p<10⁻¹⁶) trends are shown for Corona Radiata (age-of-peak (AOP)=27.9±5.7 years). Quadratic (thin curve, FA=0.45+1.3×10⁻⁴×age−0.01×10⁻⁴×age², r=0.17, p=0.03) trend is also shown for the Cortical-Spinal tract where the model was not significant and age-of-peak could not be calculated.

By-tract FA rate of decline versus by-tract FA rate of maturation.