PRNP and Alzheimer disease: This may — at least in part — explain the protective effects of PrP-directed antibodies found in diverse cellular and animal models of prion diseases and AD (Chung et al. 2010; Enari et al. 2001; Féraudet et al. 2005; Freir et al. 2011; Gilch et al. 2003; Heppner et al. 2001; Laurén et al. 2009; Peretz et al. 2001).