Table 4.
Stepwise backward linear regression analyses
| Independent variables | p value | β (95% CI) |
|---|---|---|
| Executive functioning (R2 = 0.215) | ||
| MD right SLF | <0.001 | –0.39 (−0.56 to −0.22) |
| Brain atrophy (BPF) | 0.027 | 0.18 (0.02 to 0.34) |
| Presence of lacunes | 0.020 | 0.19 (0.03 to 0.34) |
| Psychomotor speed (R2 = 0.246) | ||
| MD left CST | 0.053 | –0.18 (−0.36 to 0.00) |
| MD WBWM | <0.001 | –0.35 (−0.53 to −0.17) |
| Education | 0.083 | 0.12 (−0.02 to 0.27) |
| Verbal memory (R2 = 0.276) | ||
| MD left uncinate fasciculus | 0.019 | –0.19 (−0.34 to −0.03) |
| Age | 0.003 | –0.25 (−0.42 to −0.09) |
| Education | 0.068 | 0.13 (−0.01 to 0.27) |
| MD WBWM | 0.012 | –0.34 (−0.60 to −0.08) |
| FA WBWM | 0.038 | –0.25 (−0.48 to −0.01) |
The final multivariable model and corresponding R2 of the stepwise backward linear regression analyses for each cognitive domain are shown. Independent variables entered in the model were age, sex, education, all conventional MRI markers (WMH volume, lacunes, nonlacunar infarcts, microbleeds, and brain atrophy), FA and MD of the whole brain white matter, and MD of strategic white matter tracts (the right SLF for executive functioning, the left CST for psychomotor speed, and the left uncinate fasciculus for verbal memory). MD of these strategic white matters tracts remained in the model, whereas many conventional MRI markers were excluded. MD, mean diffusivity; SLF, superior longitudinal fasciculus; BPF, brain parenchymal fraction; CST, corticospinal tract; WBWM, whole brain white matter; FA, fractional anisotropy.