Postoperative delirium and postoperative cognitive dysfunction （POCD） are topics of special importance in the geriatric surgical population. They are separate entities, whose relationship has yet to be fully elucidated. Although not limited to geriatric patients, the incidence and impact of both are more profound in geriatric patients. Delirium has been shown to be associated with longer and more costly hospital course and higher mortality rate or postoperative institutionalization. POCD has been associated with increased mortality, risk of leaving the labor market prematurely, and dependency on social transfer payments. Here, we review their definitions, etiology, risk factors and potential neuropathogenesis, and discuss treatment and prevention.
 

    Postoperative Cognitive Dysfunction （POCD）

    Postoperative cognitive dysfunction （POCD） is a frequent complication to surgery and described as subtle deterioration in memory, attention, speed of ***rmation processing. It is deterioration of cognition that is associated with surgery/anesthesia, especially in the elderly. The diagnosis of POCD depends on valid assessments of perioperative cognitive functions. In non-cardiac surgery, there are many risk factors of early POCD, such as age, duration of anesthesia, little education, second operation, post operation infection, respiratory complications. And the most important risk factor of late POCD is the age.

    Postoperative Delirium

    Postoperative delirium is a common postoperative complication that is associated with substantial patient morbidity and mortality, characterized by disturbance in attention and awareness （reduced orientation to the environment）。 Delirium develops acutely and tends to fluctuate, and does not in face of severely reduced level of arousal or coma. Postoperative delirium has independent adverse effects on short and long-term mortality and morbidity, including poor functional recovery, postoperative cognitive dysfunction, deterioration in quality of life, and increased costs. However, at the present time, postoperative delirium is a clinical phenomenon, and its neuropathogenesis remains unknown. This gap in knowledge has become a barrier that limits further studies, including development of potential interventions for postoperative delirium. The pathogenesis of delirium is incompletely understood, and is depended on the further research.