Scientists from the Washington University School of Medicine in St Louis have developed a blood test that could detect signs of Alzheimer’s almost 20 years before the onset of the disease. They analysed levels of a protein called amyloid beta in the blood to help predict the build-up of Alzheimer's in the brain. Experts suggest that the results bring scientists one step closer in building a reliable blood test for the disease. The blood test would be a more affordable technique than the expensive brain scans. While the results provide hope for treatment, larger studies are needed to validate the blood test.