BCHE and delirium: The cholinergic deficiency hypothesis suggests that a decrease in acetylcholine levels contributes to the development of delirium.[22] A systematic review and meta-analysis found that prophylactic use of cholinesterase inhibitors may reduce the incidence of POD in elderly patients undergoing elective surgery, although the quality of evidence was low.[116] Further high-quality studies are needed to confirm the efficacy and safety of cholinesterase inhibitors in the prevention of POD.