Effect of age on WM fascicle FA and volume, and test for difference in slope between the effect of age on WM fascicle FA and the effect of age on WM fascicle volume, in the subsamples of participants older than 8 years of age

	Effect of Age on WM Fascicle FA			Effect of Age on WM Fascicle Volume			Interaction between the Effect of Age on WM Fascicle FA and WM Fascicle Volume
	β	SD	P Value	β	SD	P Value	P Value
F1, corpus callosum	0.05	0.06	.447	−0.01	0.09	.901	.770
F2, right cingulum	0.02	0.08	.822	0.02	0.12	.847	.734
F3, left cingulum	0.03	0.09	.736	−0.10	0.11	.396	.459
F4, superior longitudinal fasciculus, right anterior part	0.03	0.08	.718	0.19	0.09	.060	.175
F5, superior longitudinal fasciculus, left anterior part	0.07	0.11	.514	0.01	0.13	.925	.852
F6, superior longitudinal fasciculus, right arcuate part	0.15^{^a}	0.06^{^a}	.042^{^a}	0.17	0.10	.111	.506
F7, superior longitudinal fasciculus, left arcuate part	0.10	0.06	.142	0.01	0.07	.860	.308
F8, superior longitudinal fasciculus, right posterior part	0.01	0.07	.868	−0.13	0.14	.360	.434
F9, superior longitudinal fasciculus, left posterior part	0.02^{^a}	0.09^{^a}	.842^{^a}	−0.22	0.12	.109	.547
F10, right inferior fronto-occipital fasciculus	0.13	0.05	.043	−0.10	0.09	.296	.072
F11, left inferior fronto-occipital fasciculus	0.14	0.07	.083	−0.16	0.07	.062	.017
F12, right inferior longitudinal fasciculus	0.06	0.08	.480	0.09	0.12	.471	.802
F13, left inferior longitudinal fasciculus	0.01	0.10	.951	0.01	0.10	.900	.983
F14, right uncinate fasciculus	0.00	0.07	.963	0.06	0.09	.533	.521
F15, left uncinate fasciculus	−0.03	0.09	.731	−0.06	0.07	.431	.641

↵a P value < .05, without correction for multiple testing.