Dementia risk may be higher for older people who have general anaesthetics

French study finds higher incidence in elderly people who have had operations

(Rex Features)

Elderly patients who undergo operations requiring a general anaesthetic may be at greater risk of developing dementia, researchers warn today.

A study of more than 9,000 adults with an average age of 75 found the risk of suffering dementia was raised by a third in those who had had a general anaesthetic up to a decade earlier.

It is common for people immediately following general anaesthetic to have short-term difficulties with speaking and thinking. The condition, known as post-operative cognitive dysfunction (POCD), is thought to be caused by inflammation of nerve fibres in the brain. But it is not known whether POCD is associated with the later development of dementia.

Researchers at the French National Institute of Health and Medical Research (Inserm) and the University of Bordeaux interviewed almost 9,300 residents over the age of 65 in three French cities and monitored them for a decade. After two years one in five (19 per cent) reported having had a general anaesthetic. Over the following eight years almost one in ten (9 per cent) of the entire group developed dementia.

Dr Francois Sztark, who led the study due to be presented to the Euroanaesthesia Congress in Barcelona today, said the results showed a 35 per cent increase in the risk of dementia among those who had had a general anaesthetic during the first two years of the study.

Dr Sztark said: “There is a lot of data suggesting potential neurotoxicity of anaesthetic agents. However general anaesthesia often cannot be avoided regardless of patient age. We need other studies to understand the mechanisms involved in anaesthesia-induced neurotoxicity, and to develop strategies for avoiding potential neurotoxicity.”

Dr Eric Karran, the director of research at Alzheimer’s Research UK, said: “Research into the impact of anaesthetics on dementia is challenging because it can be very difficult to tease out cause and effect. Dementia is caused by several brain diseases, many of which arise from a complex mix of genetic and environment factors.”