APP and supranuclear palsy, progressive, 1: It has been reported that decreased CSF Aβ42 in PSP may be associated with disease severity, which may lead to a decrease in total APP-derived peptides including both Aβ42 and Aβ40 [24]; therefore, using the current standard approach of using the CSF Aβ42/40 ratio [55] (as in the patient in Supplementary Fig. 7) may be more specific to evaluate brain amyloid pathology in PSP/CBD, as has been recently suggested [56].