To bring new elements in the discussion, we investigated the pattern of Aβ deposition in the parenchyma (plaques) and in blood vessels (CAA) and characterized Aβ species from postmortem brains of patients overexpressing the APP gene, thus overproducing Aβ peptides (APPdup, DS, and DS-AD) and compared them to patients with sAD or others carrying missense mutations in the APP gene (APPV717L and APPV717I) and controls. The gene discussed is APP; the disease is Alzheimer disease.