MAPT and Alzheimer disease: Reported literature suggests that 70% of patients have tau-negative ubiquitin positive pathology with a TAR DNA binding protein (TDP-43), 20% tau-positive Pick’disease, and 10% have AD pathology.[23, 39, 62, 63] In a recent study of 100 patients with SD, 24 had autopsy – 18 had FTD-U (13/13 TDP-43 positive), 3 had classical tau pathology, and 3 had AD.