Plasma GFAP levels are approximately 1.5- to twofold higher in PSP compared to healthy controls (HC) (median: 235.5 pg/mL; range: 187.5–312.7 in PSP vs. 121.9 pg/mL; range: 91.2–156.3 in HC), and they correlate with tau deposition as measured by 18F-PI-2620 PET [53, 61]. Here, GFAP is linked to supranuclear palsy, progressive, 1.