MAPT and Alzheimer disease: In PART, the severity of tau pathology in CA1 and subiculum was high, followed by EC, CA2/3, CA4, and DG, whereas there were no essential differences in tau pathology between AD and PART at Braak stages III and IV, and PART cases (Braak stages III–IV) showed slightly more tau positive neurons in CA1 than CA2/3.