In this study, we have therefore measured the gene expression of ACE1 and ACE2, and the RAS receptors AGTR1, AGTR2, and MAS1, in normal aging and an independent case–control study comprising pure AD, mixed AD/VaD (mixed dementia), and vascular dementia (VaD), stratified according to Braak tangle stage as a marker of disease stage in AD. The gene discussed is ACE; the disease is Alzheimer disease.