MME and Alzheimer disease: It has also been shown that NEP mRNA and protein expression levels are reduced in association with age or in AD subjects (Reilly, 2001; Yasojima et al., 2001a,b; Iwata et al., 2002; Apelt et al., 2003; Caccamo et al., 2005; Maruyama et al., 2005; Wang et al., 2005, 2010); however, this notion has been seriously challenged more recently.