MAPT and supranuclear palsy, progressive, 1: Williams et al. noted in 2007 that the mean severity of pathology in all regions of the PSP-RS group (n = 22) was higher than in PSP-P (n = 14) and PSP with pure akinesia with gait freezing (currently called PSP-PGF, n = 6), and the overall tau load was significantly higher in PSP-RS than in PSP-P.