PPIB and Alzheimer disease: Moreover our findings of no differences when comparing the levels of plasma biomarkers between PET-Αβ-negative to PET-Aβ-positive LBD are in contrast with previous work suggesting that p-tau181 discriminates LBD cases with and without AD pathology; however that study used CSF Aβ42/40 and PET-tau instead of PET-Αβ.24 There can be several factors affecting our results.