Olfactory Dysfunction as a Predictive Biomarker for Postoperative Delirium Risk Assessment

Postoperative delirium (POD) is a frequent, serious complication following major surgery, especially among older adults and those with preexisting cognitive vulnerabilities. It contributes to substantial morbidity, prolonged hospital stays, institutionalization, and mortality. Despite its burden, there are few simple, effective tools to predict which patients will develop POD. Olfactory dysfunction (OD) is an early, sensitive marker of neurodegenerative and psychiatric disorders and has been recently implicated in COVID-19-associated brain changes. OD frequently reflects subclinical brain pathology, involving regions responsible for memory, attention, and cognition—critical in delirium development. Emerging evidence suggests that preoperative OD may predict POD, particularly in cardiac surgery. This review synthesizes the clinical and mechanistic links between OD and cognitive vulnerability and proposes OD assessment as a practical, noninvasive strategy for preoperative POD risk stratification. Future research should standardize olfactory testing modalities, validate predictive models, and examine whether OD-guided interventions can improve postoperative cognitive outcomes.