A new public health threat looms on the horizon: surgery requiring anaesthesia. A worrying study from Taiwan published recently reports that the risk of dementia is almost doubled in patients over 50 who receive regional or general anaesthetics. The prospective population study was controlled for variations in age, gender and other factors but it is, of course, a truism that healthy people get less surgery than unhealthy ones. However, the authors conclude that the combination of surgery and anaesthesia does seem to increase the risk of dementia (although they say it is impossible to determine which is responsible for what part of the increase). Medscape says that this is the latest piece of evidence suggesting that anaesthesia may cause accelerated cognitive decline.

Dementia is very expensive for governments in middle and upper income countries so this emerging body of evidence will change calculations about the cost effectiveness of interventions which reduce the need for surgery — these range from cholesterol-lowering agents to treatments which reduce the likelihood of  fractures linked to osteoporosis. Surgery looks even less appealing for policymakers as the threat from antibiotic resistance grows.