Unraveling the role of polyamine metabolism in postoperative delirium: insights into biochemical mechanisms and biomarker potential.

Postoperative delirium (POD) is a common complication in older surgical patients, linked to long-term cognitive decline and progression to dementia, yet its mechanisms remain unclear. We investigated arginine-related metabolites (ARMs) in cerebrospinal fluid (CSF) from 248 patients undergoing elective-surgery: 25 developed POD. Targeted mass spectrometry, gene expression profiling, and machine learning were applied to identify metabolic predictors. POD patients showed significant correlations with citrulline, ornithine, and glutamine, while models highlighted glutamine, glutamic acid, putrescine, N1-acetylspermidine, and spermidine as key biomarkers, achieving >77% predictive accuracy. Cluster and pathway analyses revealed POD-specific shifts in GABA synthesis and polyamine metabolism, contrasting with urea cycle dominance in non-POD cases. Associations persisted after adjusting for age and CSF Aβ42. Preoperative profiles in polyamine metabolism, ammonia detoxification, and neurotransmitter regulation suggest underlying neuroinflammatory and oxidative stress vulnerabilities that reduce resilience. Targeting polyamine biosynthesis may offer novel preventative and therapeutic strategies to mitigate POD and dementia risk.