MAPT and Alzheimer disease: The 33 KDa/55 KDa tau isoforms ratio have also been found to be normal in PD (Borroni et al., 2008, 2009), but decreased in progressive supranuclear palsy (PSP), and normal in patients with diffuse Lewy body disease (DLBD), demented PD patients (PDD), AD, and frontotemporal dementia (FTD) (Borroni et al., 2008, 2009).