MAPT and Alzheimer disease: The accumulation of Aβ peptides and hyperphosphorylated Tau are hallmarks of AD, and cathepsin D is responsible for the generation of Aβ peptides and be correlated with the hyperphosphorylation of Tau.157,177,178 In addition, elevated cathepsin B in the serum has been shown to be identified significant correlated with cognitive dysfunction in patents with AD.175,179