MAPT and Alzheimer disease: We obtained an average Kd value of 25.7 ± 3.7 nM in AD tissue IF, and the specific to nonspecific ratio for the AD tissue homogenate assay was much higher compared to the PD tissue homogenate assay, which is likely explained by the substantially higher concentration of Aβ and tau fibrils in AD tissue compared to the concentration of Asyn fibrils in PD tissue.