A trial has begun to see whether a drug used to treat diabetes can slow the progression of Alzheimer's disease.
The study will involve 200 patients with memory problems due to early Alzheimer's. Laboratory research suggests that the drug, liraglutide, reduces brain inflammation, improving the growth of brain cells and the connections between them.
Patients will be recruited in London - at Imperial College and King's College - and sites in Oxford, Southampton and Swindon.
One of those on the trial is 65-year-old Geoff Payne. He became concerned about short-term memory loss three years ago and was eventually diagnosed with Alzheimer's.
"My older brother died of Alzheimer's at the age of 79," he said.
"His disease was spotted quite late and I remember him being almost entirely silent and withdrawn at family gatherings.
"I wish I'd tried to talk more to him about it. When I finally got my diagnosis it confirmed my own suspicions. I have had the disease for three years but fortunately I have not yet declined substantially.
"My wife and I know what to expect in the years ahead, so we take one day at a time. Hopefully this drug may help."
Those on the trial will receive a daily injection of liraglutide or a placebo for 12 months. They will have scans and memory tests before and after the treatment.
It's a decade since the last new treatment for Alzheimer's was introduced and some major drug trials have failed in recent years.
"New drugs can take decades to filter through and cost billions," said Dr Paul Edison, Imperial College London, who's leading the trial.
"Liraglutide is a tried and tested diabetes treatment, so we know it is safe. This trial will show within three years whether it can slow the progression of Alzheimer's."
Alzheimer's Society is providing more than £300,000 towards the project. Dr Doug Brown, Director of Research and Development said: "This exciting study suggests that one of these drugs can reverse the biological causes of Alzheimer's even in the late stages and demonstrates we're on the right track.
"We are now funding a major new trial to bring it closer to a position where it can be improving the lives of people with dementia.'
The need for more research and new treatments will be the key focus of the G8 dementia summit in London on Wednesday.
The Department of Health says health ministers will discuss how they can coordinate and accelerate efforts and try to break down barriers between companies, researchers and clinicians.
Dementia is already a significant global issue, and cases are predicted to rise from 44 million to 135 million by 2050 - a reflection of the growing and ageing global population.
It is thought to cost the global economy £370bn ($604bn) each year and there are concerns that future demands could overwhelm some health services.