Fig 1.
Flow diagram of the overall study: participant selection, TBSS analysis, and statistical analysis.
DTI, diffusion tensor imaging; TBSS, tract-based spatial statistics; FSL, FMRIB Software Library; AxD, axial diffusivity; RD, radial diffusivity; CDR, clinical dementia rating.
Table 1.
Demographic characteristics of the participants and the cognitive assessment score.
Fig 2.
TBSS results showing significant AxD and RD changes at baseline and the follow-up.
The regions indicated in green represent the mean white matter skeleton, whereas the regions indicated in red represent the regions with increased AxD (first row) and RD (second row). The decreased diffusivity metrics (AxD and RD) exhibited no statistically significant differences at P < 0.05 after correcting for multiple comparisons (FWE). The color intensity follows the Red–Yellow scale, where red represents stronger statistical significance (closer to P = 0.05), and the color transitions towards yellow as the P-value approaches zero. TBSS, tract-based spatial statistics; AxD, axial diffusivity; RD, radial diffusivity; FWE, family-wise error; FM, forceps minor; ACR, anterior corona radiata; CCS, splenium of corpus callosum; PCR, posterior corona radiata; SS, sagittal stratum; CCG, genu of corpus callosum; SCR, superior corona radiata; PTR, posterior thalamus radiation; CG, cingulum cingulate gyrus; SLF, superior longitudinal fasciculus; IFOF, inferior fronto-occipital fasciculus; ILF, inferior longitudinal fasciculus.
Table 2.
Anatomic locations exhibiting significant changes in AxD and RD.
Table 3.
Correlation between AxD and RD in specific white matter regions and CDR scores.
Fig 3.
Partial correlation plots showing the association between AxD change and CDR change in four significant white matter regions: (a) left RIC, (b) left PCR, (c) left FST, and (d) right SLF.
All values were residualized after adjusting for age, sex, education, APOE ε4 status, and baseline CDR. Solid black lines indicate the linear trend, and shaded areas represent the 95% confidence intervals. Each dot corresponds to an individual participant. Spearman’s correlation coefficients and P values are reported above each panel. AxD, axial diffusivity; RIC, retrolenticular part of internal capsule; PCR, posterior corona radiata; FST, fornix cres stria terminalis; SLF, superior longitudinal fasciculus.