Since neuroinflammation has been considered a major mechanism for POCD and neuroinflammation impairs learning and memory,4, 9, 35, 36 a possible pathway for POCD is surgery‐neuroinflammation‐HDAC activation‐neuroligin 1 decrease‐synapse impairment‐learning and memory impairment. This evidence concerns the gene HDAC9 and memory impairment.