“Postoperative cognitive dysfunction (POCD) is a decline in cognitive function (especially in memory and executive functions) that may last from 1–12 months after surgery, or longer. In some cases, this disorder may persist for several years after major surgery. POCD is distinct from emergence delirium. Its causes are under investigation and occurs commonly in older patients and those with pre-existing cognitive impairment.
The causes of POCD are not understood. It does not appear to be caused by lack of oxygen or impaired blood flow to the brain and is equally likely under regional and general anesthesia”
Also see : General Anaesthetics