[Postoperative cognitive dysfunction: Preface and Comments]

Postoperative cognitive dysfunction (POCD) has been highlighted over a decade. Although perioperative stroke is obvious central nervous system pathology, POCD is often subtle and unrecognized. No consensus on the definition for POCD has been reached. POCD may be attributed to preoperative, surgical, anesthetic, or adverse perioperative events. POCD often occurs frequently in elderly patients even after minor surgical procedures. POCD may last years after surgery and may impair the patient's social activity including premature departure from the workforce. Although neuroinflammation is suggested as an important predisposing factor, our knowledge on other predisposing factors is limited and effective preventive measure is unknown.