Hundreds of thousands of Australians are believed to be suffering memory loss for months after surgery and there are fears it could be causing dementia in people over 65.

The trend has prompted research into whose brains are most vulnerable and whether there are ways to prevent or treat cognitive deficits in people having surgery.

Director of anaesthesia at St Vincent's Hospital in Melbourne, David Scott: "We treat their heart really well but we do nothing for the brain." Credit:Louie Douvis

A meeting of anaesthetists in Singapore heard that while many patients experience confusion after waking from operations, one-third, or about 264,000, of the 800,000 Australians over 65 having operations each year are showing cognitive deficits one week after surgery. And about one in five or 160,000 people over the age of 65 are still suffering mentally three months on.

Lis Evered, the research manager of the Centre for Anaesthesia and Cognitive Function at St Vincent’s Hospital in Melbourne, said studies also suggested surgery could be triggering dementia in people who have subtle memory loss before surgery. Associate Professor Evered told the conference that a study of 67 Victorians with mild cognitive impairment before surgery showed 43 per cent of them had dementia one year on.