PDGFRB and Alzheimer disease: We previously reported that oxygenation of both the precuneus and the underlyingwhite matter was reduced in the early stages of AD.26 Present findings show the reduced oxygenation of the precuneus to beassociated with loss of the pericyte protein PDGFRB, and the accumulation offibrinogen and Aβ (particularly plaque-associated fibrillar Aβ).