Although ACE is believed to convert neurotoxic Aβ42 peptides into a shorter form of Aβ40, thought to be less toxic in AD, the manner in which ACE inhibition affects amyloid peptide forms in AD is not yet well understood (Eckman et al., 2006; Zou et al., 2007, 2013; Regenold et al., 2017). Here, ACE is linked to Alzheimer disease.