APOE and Alzheimer disease: The clinical manifestations and pathogenesis of POCD and AD are similar, involving tau protein and Aβ plaques, central cholinergic injury, apolipoprotein E (ApoE) gene mutation, etc. It has been found that in patients undergoing hip replacement under subarachnoid anesthesia, IL-1β, Tau/Aβ1-42, pTau/Aβ1-42 and Aβ1-42 in the cerebrospinal fluid of POCD patients increased significantly, compared with the non-POCD group (Ji et al., 2013).