Cognitive decline in the elderly: is anaesthesia implicated?

Overview

Postoperative cognitive dysfunction (POCD) was originally thought to be associated with cardiac surgery, but has since been associated with non-cardiac surgery and even sedation for non-invasive procedures such as coronary angiography. The focus of POCD has thus shifted from the type of surgery or anaesthetic to patient susceptibility. The realisation that cognitive impairment, such as mild cognitive impairment (MCI - the prodrome for Alzheimer's disease (AD)), may already exist in many elderly patients who incidentally present for surgery beckons anaesthesia to align cognitive research with that of AD in order to draw valid parallels between the two disciplines. Long-term studies are required to understand if POCD is merely a transient phenomenon, or if it is the harbinger of long-term cognitive deterioration which may lead eventually to dementia. In this regard, the use of CSF analysis to diagnose AD many years before symptoms appear may identify susceptible individuals. Furthermore, animal studies indicate that volatile anaesthestics may augment the pathological processes of AD by affecting amyloid-beta processing. Identification of a link between surgery/anaesthesia, POCD, MCI, and AD would create a unique opportunity to fast-track the development of clinical or pharmacological preventive strategies that would benefit a significant proportion of the population.