Table 3.

Summary of linear mixed models examining tract-specific FA on cognitive change (controlling for modified global FA)

Region	Estimate	Standard error	t-value	P-value
Executive function
ATR	0.010	0.010	0.982	0.163
CB	0.026	0.011	2.326	0.010
PHC	−0.006	0.009	−0.715	0.737
CST	−0.003	0.010	−0.270	0.894
Fma	0.005	0.011	0.466	0.321
Fmi	0.007	0.012	0.587	0.279
IFOF	0.013	0.015	0.871	0.192
ILF	−0.023	0.011	−2.089	0.518
SLF	−0.012	0.014	−0.912	0.681
Episodic memory
ATR	0.009	0.014	0.603	0.273
CB	0.025	0.016	1.563	0.059
PHC	−0.008	0.012	−0.608	0.772
CST	−0.006	0.014	−0.450	0.826
Fma	0.005	0.015	0.346	0.365
Fmi	0.023	0.017	1.359	0.087
IFOF	−0.013	0.021	−0.620	0.768
ILF	−0.006	0.016	−0.406	0.842
SLF	0.012	0.019	0.636	0.263
Processing speed
ATR	0.021	0.012	1.820	0.035
CB	0.007	0.013	0.501	0.308
PHC	−0.005	0.010	−0.517	0.803
CST	−0.011	0.012	−0.919	0.679
Fma	0.015	0.012	1.173	0.121
Fmi	0.012	0.014	0.901	0.184
IFOF	0.036	0.017	2.109	0.018
ILF	0.004	0.013	0.310	0.379
SLF	−0.036	0.015	−2.320	0.510

Each row summarizes the results from a separate linear mixed model that examines the contribution of each tract over and above a global measure of white matter microstructure to longitudinal cognitive change. All models control for age, sex, education, motion in the scanner, modified global FA, amyloid status, and their interactions with time. The modified global FA does not include the specific tract under investigation. After accounting for modified global FA and multiple comparisons (P < 0.006), none of the individual tracts predicted a significant change in cognitive performance. FA, fractional anisotropy; ATR, anterior thalamic radiation; CB, cingulum bundle; PHC, parahippocampal cingulum; CST, coticospinal tract; IFOF, inferior frontal occipital fasciculus; ILF, inferior longitudinal fasciculus; Fma, forceps major; Fmi, forceps minor; SLF, superior longitudinal fasciculus.