Table 6.

Mean and standard deviation of tract mean FA in the anterior callosal fiber (ACF) bundle, and in left and right hemispheres (LH, RH) of the corticospinal tract (CST) at baseline (Wave-1) and at follow-up 3 years lager (Wave-2).

Tract	Wave-1	Wave-2	P-value	N	% ΔFA/year	M
ACF	0.437 ± 0.033	0.420 ± 0.028	<0.001	74	−1.50	1
LH CST	0.434 ± 0.025	0.439 ± 0.023	0.014	76	0.49	0
RH CST	0.424 ± 0.027	0.427 ± 0.028	0.058	74	0.36	2

The percentage annual change of tract mean FA (calculated first for each subject and than averaged across the total sample) is given in column 6. N (≤ 24; column 6) denotes the total number of subjects for which the specific fiber bundle could be identified according to the given criteria. M (column 7) denotes the number of participants discarded by the exclusion criteria of having tract mean FA larger than 2.5 SD with respect to the FA variation in the whole sample. P-value (column 4) is calculated from paired-samples t-test assuming null hypothesis of no change in tract mean FA between Wave-1 and Wave-2. Significant change is marked by bold values.