The incidence of postoperative cognitive dysfunction (POCD) is often underestimated and not intuitively present by many anesthetists. POCD often occurs in the elderly but is also seen in younger patients. The incidence of POCD 1 week after non-cardiac surgery covers a span between 19-41% in patients older than 18 years. An increased POCD rate (10%) 3 months after surgery is only detected in patients older than 60 years. The occurrence of POCD is associated with an increased mortality rate, jet the etiology is mainly unknown despite enormous research efforts. The age of the patient is one of the main risk factors for the development of POCD. Data on how to avoid POCD are limited. However, the maintenance of homoeostasis is an important cornerstone of prophylaxis.