Top and bottom Prussian blue-positivity quartile differences in Sclerosis Index (SI). Top and bottom Prussian blue positivity quartile differences in SI in the following brain regions taken separately and collectively: Striatum at the level of the mammillary bodies (BG2), calcarine/pericalcarine cortex (OCC), middle frontal gyrus (MF), rostral cingulate cortex (CGA), caudal cingulate cortex (CGP). (A) SI was significantly higher in the top quartile versus bottom quartile in the MF brain region (0.410 ± 0.015 vs 0.358 ± 0.018; p < 0.05), in the CGA region (0.376 ± 0.010 vs 0.341 ± 0.013; p < 0.05), and in all 5 brain regions taken collectively (0.379 ± 0.007 vs 0.355 ± 0.008; p < 0.05). (B, C) SI in the bottom and top quartiles, respectively, under 60× magnification. *p < 0.05.