Tests carried out on mice have revealed changes in their brains, similar to those observed in humans with dementia, when the animals are operated on.
The researchers suspect the same effect could occur in humans after surgical procedures and are now to start a new study to further explore the theory.
Many doctors already suspect there may be a link between surgery and the onset of Alzheimer's.
Previous studies have suggested that between 10 and 30 per cent of elderly people who undergo surgery suffer memory problems afterwards, but it has not been established whether these are a short-term response to physical trauma, or the beginnings of dementia.
Cognitive problems, ranging from memory loss to delirium, have been found most commonly when elderly people have undergone heart surgery, but also following other operations.
It is not known if the procedures themselves, or the body's response to major trauma, spark changes in the brain.
The latest research, conducted at Imperial College London and due to be published in the journal Critical Care Medicine next month, shows that the brains of mice who underwent a surgical procedure showed the presence of protein "tangles" in the brain which are associated with Alzheimer's disease in humans.
Because normal mice do not develop Alzheimer's disease, the new two-year study, also being led by Imperial College, will examine genetically modified mice, in an attempt to see whether the tangles – clusters of protein that form in nerve cells – which are present after surgery go on to trigger the onset of dementia.
The study will also examine whether the use of certain drugs – such as statins, used to protect against heart disease – and the active ingredient of a herbal remedy called Celastrol, could reduce the risks for those undergoing surgery.
In the recent study on mice, Celastrol was seen to reduce inflammation in the brain.
Researchers said if either drug appeared to lower the risks of dementia in modified mice undergoing surgery, further trials would be required to see if this worked in humans, and also to see if it could protect the brains of the wider population, not just those undergoing operations.
Dr Daqing Ma, the lead investigator on the research said: "The data has shown for some time that some elderly people who undergo surgery, especially heart surgery, can develop cognitive dysfunction, which can mean memory loss, and a loss of focus but it isn't clear how much of that is short-term, and how much long-term.
"Some people go on develop dementia, which can damage lives and mean an early death, but we don't know if there is a link with the cognitive dysfunction suffered post-surgery."
Previous studies had examined the extent of dementia within groups who had experienced surgery.
But given that an increasing number of elderly people now undergo operations, it has so far proved impossible to demonstrate that the procedures themselves triggered the dementia.
Anecdotally, many doctors believe they have seen cases which might have been triggered by surgery, said Dr Ma.
He cited the example of former US President Ronald Reagan, who underwent several surgical operations in the course of his life, including emergency brain surgery in 1989, after falling from a horse, five years before he was diagnosed with Alzheimer's.
His wife Nancy has said she believes the incident hastened the onset of the disease. Mr Reagan also underwent emergency surgery following an assassination attempt in 1981, and several surgical procedures for cancer.
Doctor Suzanne Sorensen, head of research at the Alzheimer's Society, which is sponsoring the research along with the Bupa Foundation, said the study was important, because of the high numbers of elderly people who undergo one sort of surgery or another.
She said: "We know from what previous studies have shown that between 10 and 30% of elderly people suffer some kind of cognitive problems after surgery, and the numbers are highest in the most elderly people.
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