Table 1.

Statistical relationships between mean white matter values and age for each metric. The second and third columns contains the F-statistic and p-value derived from the penalized spline for age in each GAM. The fourth column contains change in R² between polynomial models only accounting for sex and head motion effects and those that include age terms as well. The last column represents the age range at which the 95 % confidence interval for the estimated age effect does not include 0 in each GAM.

Metric	FAge	pAge	ΔR2	Age Spline Slope CI ≠ 0
msFA	4.24	0.034	0.116	12.7−21.3
msMD	14.04	1.20 × 10−5	0.222	12.7−22.9
msAD	14.37	2.07 × 10−5	0.184	12.7−23.8
msRD	10.33	2.16 × 10−4	0.193	12.7−22.4
ssFA	4.91	0.018	0.136	12.7−21.4
ssMD	6.12	0.001	0.123	12.7−22.2
ssAD	6.57	0.012	0.061	NA
ssRD	5.83	0.010	0.139	12.7−21.9
ICVF	18.23	3.41 × 10−7	0.246	12.7−23.0
ODI	5.66	0.019	0.060	NA
ISOVF	5.55	0.020	0.057	NA
RTOP	15.20	2.77 × 10−6	0.247	12.7−22.4
RTAP	13.17	1.64 × 10−5	0.223	12.7−22.4
RTPP	13.87	1.01 × 10−5	0.204	12.7−22.6