MAPT and supranuclear palsy, progressive, 1: The presence of concomitant Alzheimer pathology is not rare; it has been reported in up to 36% of pathologically confirmed PSP.[19] A concomitant presence of 3-repeat (RD3) isoform of tau protein is considered to be an important risk factor for developing Alzheimer pathology accompanying PSP.[20] The presence of RD3 isoform of tau protein was detected in some areas of the temporal lobe in our second case.