The role of NSE and Tau proteins in identifying Sepsis-associated Delirium: a cross- sectional pilot study

Abstract Background Sepsis-associated delirium is a cerebral manifestation commonly occurring in patients with sepsis and is thought to occur due to a combination of neuroinflammation and disturbances in cerebral perfusion, the blood brain barrier (BBB) and neurotransmission. This cross-sectional pilot study aims to evaluate plasma levels and possible correlation between brain cell damage biomarkers (neuron-specific enolase [NSE] and Tau proteins) in patients with delirium and sepsis, and to obtain tools that identify sepsis in patients with delirium admitted in the Emergency Department. Results We analyzed 25 patients, and 14 (56%) had sepsis. Septic patients had higher NSE (2.7ng/mL, [95% CI: 2.2–3.2] vs. 1.7ng/mL, [95% CI: 0.8–2.5], p < 0.003) and Tau (94.2pg/mL, [95% CI: 77.0-111.3] vs. 57.8pg/mL, [95% CI 31.2–84.5], p < 0.003) than non-septic patients. The best cutoffs for NSE and Tau protein were 2.08ng/mL (LR positive: 4.71, LR negative: 0.17) and 59.27pg/mL (LR positive 3.40, LR negative: 0.09) respectively. We found a 90% specificity for developing sepsis in patients with both NSE above 1.59ng/mL and Tau above 59.27pg/mL. Conclusions NSE and Tau proteins, biomarkers of brain injury, are higher in septic patients than non-septic when analyzed older patients with delirium. Therefore, we suggest that plasma levels of these proteins may be further studied as tools to identify infectious etiology of delirium in older patients in Emergency Departments.