Recent evidence suggests that AD-associated itch is mediated by a broad spectrum of signaling molecules, including pro-inflammatory cytokines such as IL-31 (Duca et al., 2022), IL-33 (Nakajima et al., 2021) and TSLP (Meng J. et al., 2021); sensory ion channels such as members of the transient receptor potential (TRP) family (Meng J. et al., 2021); immune effector events such as IgE-mediated mast cell degranulation (Mollanazar et al., 2016); and proteolytic mediators including Cathepsin S (CTSS) (Ruppenstein et al., 2021). This evidence concerns the gene CTSS and Alzheimer disease.