Table 1.

Age group differences in white matter integrity

	FA			AD(× 10−3 mm2/sec)			RD(× 10−4 mm2/sec)
Tracts	Younger	Older	t	Younger	Older	t	Younger	Older	t
ILF Left	.59 ± .03	.54 ± .04	−4.5*	1.34 ± 0.04	1.29 ± 0.06	−2.9*	4.78 ± 0.29	5.12 ± 0.37	2.9*
ILF Right	.57 ± .04	.53 ± .03	−3.0*	1.30 ± 0.05	1.27 ± 0.06	−1.4	4.82 ± 0.37	5.18 ± 0.34	2.9*
SLF Left	.49 ± .05	.47 ± .03	−1.8	1.08 ± 0.04	1.09 ± 0.05	0.2	4.94 ± 0.39	5.21 ± 0.29	2.3†
SLF Right	.47 ± .05	.45 ± .03	−1.2	1.07 ± 0.04	1.08 ± 0.05	0.7	5.13 ± 0.39	5.37 ± 0.28	2.1*
Genu	.53 ± .03	.48 ± .03	−4.2*	1.30 ± 0.05	1.31 ± 0.06	0.1	5.11 ± 0.35	5.77 ± 0.55	3.8*
Splenium	.61 ± .03	.60 ± .03	−0.6	1.50 ± 0.09	1.47 ± 0.06	−0.9	5.05 ± 0.52	5.03 ± 0.31	−0.1

Notes. Fractional anisotropy (FA), axial diffusivity (AD), and radial diffusivity (RD) values are presented as mean ± standard deviation for each white matter tract separately for younger and older adults.

^*significant effects at p < .008 (Bonferroni-corrected for 6 comparisons per measure of white matter integrity).

^†significant effects at p < .05.

ILF = inferior longitudinal fasciculus. SLF = superior longitudinal fasciculus.