The reduced Wnt signaling tone evident in AD is at least partially because of Aβ fibril-induced upregulation of DKK1/Dkk1 in human AD and AD mouse models (Caricasole et al., 2004; Rosi et al., 2010; Killick et al., 2014; Sellers et al., 2018; Jackson et al., 2019). Here, DKK1 is linked to Alzheimer disease.