MAPT and brain injury: Plasma levels of NSE and Tau protein have been associated with brain injury and delirium.23,24 Neuron-specific enolase is a promising peripheral blood marker of brain injury as it is a cytosolic enzyme primarily expressed in neurons and neuroendocrine cells, with a high concentration in the brain.25 Neuron-specific enolase has demonstrated value in assessing the severity of brain injury and early prognosis following traumatic brain injury,26 cardiac arrest,27 and sepsis.28