Alzheimer's test raises hopes of prevention
A blood test has been found to be 94pc accurate at detecting Alzheimer's disease before people develop memory loss and confusion.
Researchers from Washington University School of Medicine in St Louis can now measure tiny levels of amyloid beta protein in the blood, and use levels to predict how much has accumulated in the brain.
Although the causes of Alzheimer's are still unknown, the disease leads to a build-up of sticky amyloid plaques in the brain, which prevent neurons from communicating with each other, setting off a cascade of further damage.
But scientists now know that amyloid is already building up in the brain up to 20 years before any symptoms show, which can be seen on brain scans.
Researchers found that when blood amyloid levels are combined with two other major risk factors - age and the presence of the gene mutation APOE4 - scientists could spot the disease before it emerged.
The test is important because many scientists now believe the brain damage of Alzheimer's is impossible to reverse and are now looking for drugs which would prevent the harm from occurring in the first place.
And if scientists knew who would get the disease they could carry out trials on preventative drugs which could stop the condition from ever developing.
"Right now we screen people for clinical trials with brain scans, which is time-consuming and expensive, and enrolling participants takes years," said senior author Dr Randall Bateman.
"But with a blood test, we could potentially screen thousands of people a month. That means we can more efficiently enrol participants in clinical trials."