MAPT and Atrophy: This finding is in contrast to a recent [18F]AV‐1451/PET study showing the best intergroup differentiation achieved using radioligand retentions in the globus pallidus.17 It is likely that damaged neurons along with PBB3‐positive tau inclusions are eliminated as the disease advances and marked atrophy attributed to tau‐induced neurotoxicity results in a partial volume effect on radioligand binding measures,24, 28, 29, 30 leading to underestimation of BP*ND values for [11C]PBB3 in advanced PSP cases.