Alzheimer's blood test 'one step closer'

­Researchers say they can accurately identify people on track to develop Alzheimer's disease before symptoms appear, which could help the progress of drug trials. US scientists were able to use levels of a protein in the blood to help predict its build-up in the brain. UK experts said the results were promising - and a step towards a reliable blood test for Alzheimer's to speed up dementia research. But larger studies were needed first. Researchers from Washington University School of Medicine, in St Louis, Missouri, writing in Neurology, measured levels of one protein, called amyloid beta, in the blood of 158 adults aged over 50 to see if this matched levels found in brain scans. It did, but only 88% of the time - which is not accurate enough for a diagnostic test. When the researchers combined this information with two other risk factors for the disease - an age of over 65 and people with a genetic variant called APOE4, which at least triples the risk of the disease - the accuracy of the blood test improved to 94%.