Fig. 3.

NII detects decreased FA and increased radial diffusivity in the early symptomatic AD when compared to preclinical AD and healthy controls. Coronal, axial and sagittal views show the voxels (red/yellow clusters, expanded to be visible) in which (1) FA significantly (P < .05) decreased in early symptomatic AD after multiple comparison when compared to the healthy controls (A) and the preclinical AD (B) cohorts; (2) radial diffusivity significantly increased in the early symptomatic AD cohort when compared to the healthy controls (C) and the preclinical AD (D) cohorts. The mean FA skeleton (green) representing the centers of all WM tracts common to participants was overlaid on the Montreal Neurological Institute standard space brain T1-weighted image. (E) Boxplot demonstrates that, in the region of genu of corpus callosum, the FA (a) is significantly decreased and radial diffusivity (b) is significantly increased in the early symptomatic AD when compared to that in the preclinical AD and the healthy controls cohorts. Thick lines indicate means, boxes indicate 25th to 75th percentiles, and thin lines indicate 5th and 95th percentiles. The age, gender, and APOE ε4 genotype were controlled for in computing the statistical significance of differences. L, left hemisphere; R, right hemisphere; P, posterior; A, anterior; *P < .05. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)