Biomarkers and postoperative cognitive function

Neurocognitive dysfunction after surgery is highly relevant in the elderly. The multifactorial manner of this syndrome has made it hard to define an ideal biomarker to predict individual risk and assess diagnosis and severity of delirium [postoperative delirium (POD)] and subsequent postoperative cognitive decline (POCD). This review summarizes recent literature on blood biomarkers for POD/POCD.Markers for delirium have been searched for in the cerebrospinal fluid to examine the pathologic cascade. However, cerebrospinal fluid cannot be easily obtained in the perioperative setting. Thus, attention shifts toward prediction markers from patients' blood to determine the individual risk. In this regard, three major groups of peripheral blood markers could be distinguished: first, global, but unspecific markers associated with POD/POCD; second, specific and established markers related to neurocognitive function; and third, upcoming or newly described markers with less evidence. Solely neuron-specific enolase is an adequate biomarker based on recent literature.Single markers for postoperative cognitive impairment cannot predict POD/POCD in geriatric patients. However, a wisely arranged battery of promising biomarkers might achieve a satisfying sensitivity and specificity for the preoperative assessment of subsequent cognitive decline. Adequately powered studies to prove this hypothesis are required.