The reported downregulation of somatostatin (Davies et al., 1980; Lu et al., 2004; Gahete et al., 2010), estrogen (Manly et al., 2000; Barron and Pike, 2012), and vitamin D (Annweiler et al., 2011; Llewellyn et al., 2011) in aged individuals and AD patients may explain the downregulation of NEP upon aging and in AD. The gene discussed is SST; the disease is Alzheimer disease.