Autonomic dysfunction as a predictor of postoperative cognitive disorders in older adults

Abstract

Introduction: Population aging has increased surgery in older adults, who are at higher risk of delirium and postoperative cognitive dysfunction. The autonomic nervous system is emerging as a relevant biological candidate for predicting these complications, given its role in modulating the response to surgical stress. Objective: To synthesize the available evidence on the association between biomarkers of autonomic dysfunction and the risk of delirium and postoperative cognitive dysfunction in older adults undergoing surgery. Method: Systematic review following PRISMA 2020 guidelines. PubMed/MEDLINE, Scopus, Web of Science, Embase, and Google Scholar were searched from January 2000 to February 2025. Original studies in adults over 60 years of age with preoperative, intraoperative, or postoperative autonomic measurements and postoperative cognitive assessment using validated instruments were included. Methodological quality was assessed using the Newcastle-Ottawa Scale. Results: Fourteen eligible studies were identified. Elevated intraoperative blood pressure variability predicted delirium in five independent studies involving orthopedic and cardiac surgery, showing a dose-response association. Reduced heart rate variability was associated with a higher risk of delirium in six studies, although with divergent results depending on the time of measurement. No studies on baroreflex sensitivity were identified. Evidence on sympathovagal indices is limited and methodologically heterogeneous. Conclusions: Autonomic biomarkers, particularly intraoperative blood pressure variability, show consistent potential for stratifying the risk of postoperative delirium. Prospective, multicenter studies are needed to evaluate the incremental utility of these biomarkers over conventional clinical predictors and to establish valid clinical thresholds.