MAPT and Alzheimer disease: There is strong evidence in vivo and post‐mortem that [18F]AV‐1451 binds paired helical filaments of tau in Alzheimer's disease (AD).3, 4 The distribution and magnitude of in vivo tau binding correlates with AD staging,5 and recapitulates the anatomical distribution of focal onset forms including logopenic aphasia 6 and posterior cortical atrophy.7 Binding to tau in primary, non‐AD tauopathies is less well established, with inconsistency between in vivo PET findings and post‐mortem analysis in progressive supranuclear palsy.3, 8, 9