By Gill Higgins
Health correspondent, BBC News
Doctors at Hammersmith Hospital have scanned over 60 people
Brain scanning technology may help identify how Alzheimer's disease progresses and who is likely to get the disease, researchers suggest.
Scientists at Hammersmith Hospital have scanned more than 60 people, including some with Alzheimer's, some with other memory problems and unaffected people.
The results suggest that scans using a radioactive or "glowing" dye can detect if the disease is present.
The Hammersmith team are also testing an Alzheimer's vaccine.
The (Positron Emission Tomography) PET scan technique uses a radioactive marker, known as PIB or Pittsburgh Compound-B.
This binds to a protein called amyloid which forms in the areas of the brain damaged in Alzheimer's disease.
It gives off a fluorescent glow that shows up as "hot" red and orange colours on the scan.
David Brooks, a professor in neurology at Imperial College London, said: "The scans give a much clearer idea of what's going on.
"If people come to our clinic and say they have problems with their memory, the first thing they'll want to know is if it's a serious medical condition like Alzheimer's or just that they're not getting enough sleep.
"In about 60% of cases, there's evidence of early Alzheimer's, picked up by detecting the amyloid protein.
"In the others, we can reassure them it's not Alzheimer's."
The new technique is not yet available on the NHS because a the dye it uses is being refined.
The current PIB dye has a very short half-life, so it has to be made on-site, requiring equipment known as a cyclotron.
The Imanet centre at Hammersmith, which is run by GE Healthcare and the Medical Research Council, has a cyclotron but there are very few others in the UK.
The new version of the dye will have a much longer half-life so that the dye can be transported to other centres.
However, it will not be available for several years because it will first have to be tested for safety.
The conventional diagnosis of Alzheimer's is based on a patient's symptoms.
The problem is that these normally occur much later, when the condition has been present for some time.
It is possible to see amyloid plaques in the damaged areas on autopsy after the patient has died.
But this new technique is a vast improvement, giving doctors the possibility of spotting this sign of Alzheimer's as the disease takes hold.
Early diagnosis is important not only to allow prompt treatment, but also to give time for both the patient and their family to prepare and plan for the future
The trials at Hammersmith are also testing a new treatment based on a vaccine approach.
At the moment, only drugs that treat symptoms are available. There is no cure.
The new approach involves a secretase-inhibiting drug that is designed to prevent any further build up of amyloid protein.
It is hoped this will stop the disease in its tracks.
But the research is in its early stages.
Christine Cooper has Alzheimer's
Several hundred patients have been tested at the Hammersmith site and other sites worldwide.
But scientists will need to test nearer to 10,000 before they have enough data to conclude whether this approach works.
If it does, it could lead to a revolution in Alzheimer's care.
Professor Brooks said: "We now know those at risk of Alzheimer's. For example it may run in the family.
"In principle, we'll be able to scan these patients, detect the amyloid protein, and then immunise them ahead of running into any problems."
Christine Cooper, a patient involved in the trial, developed Alzheimer's three years ago at the age of 52.
The research will be too late to help her, but she is glad to be involved in the hope of helping others.
She knows the impact that Alzheimer's can have. She no longer wants to go out by herself. She cannot cook, or go shopping. It means her husband Denis Cooper has to care for her, as well as still go out to work.
Mr Cooper said they first saw small changes.
"It was little things like Christine couldn't spell, when she used to be very good.
"We just thought it was the menopause and things like that, but other signs were there that we can only relate to now we look back, like balance and walking, just little things."