Lin X, Tang J, Liu C, et al. - Researchers examined the correlation between expression levels of cholinergic biomarkers in cerebrospinal fluid (CSF) and the occurrence and development of postoperative delirium (POD) in elderly patients. They assessed 492 elderly patients aged 65 years or older having elective total hip/knee replacement getting combined spinal-epidural anesthesia. They used the Mini-Mental State Examination (MMSE) prior to surgery to evaluate preoperative baseline cognitive function. In the post-anesthesia care unit (PACU), each patient was interviewed on the first, second, third, and seventh (or before discharge) postoperative days. Among 447 included patients, 11.4% developed POD. Patients who developed POD showed reduced concentration and activity of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) and raised concentration and activity of choline acetyltransferase (ChAT), as well as raised concentrations of IL-6 and TNF-α in preoperative CSF and preoperative and postoperative plasma, with BuChE in preoperative CSF having the most significant differences. Observations here suggest a correlation of the changes in preoperative activity of AChE, BuChE and ChAT in CSF with the development of POD in elderly patients. BuChE activity was noted to have the greatest diagnostic value, which may be linked to central cholinergic degradation. The neuropathology of POD might involve these cholinergic biomarkers.