POCD in 22 (37%) patients Decreased rSO2 in 21 (35%) patients Short term episodes of decreased rSO2 during surgery is not correlated with incidence of cognitive impairment No significant changes in the level of glial fibrillary acidic protein following surgery. Neuron-specific enolase increased in 29 (49%) of patients following surgery, but there was no association with POCD. This evidence concerns the gene ENO2 and Cognitive impairment.