A blood test that helps to detect early Alzheimer’s disease is one step closer to clinical use. When combined with measures of two major risk factors, it identifies early brain changes with 94% accuracy, researchers have found.

Alzheimer’s brain plaques develop decades before outward symptoms of the disease appear. Using a technique called mass spectrometry, the blood test can precisely detect amyloid beta protein, a telltale sign of these brain changes. A patient’s age and the presence of a genetic marker can then be factored into the diagnosis to boost the test’s accuracy, according to a recent Washington University School of Medicine study.

The test may be even more sensitive than the current gold standard of diagnosis – positron emission tomography (PET) brain scans – and is certainly less invasive and less expensive, reported the study’s senior author, Randall J. Bateman, M.D. 

He and his colleagues expect that the test may become available for clinical use within a few years. He also suggested that the test’s relative ease and lower cost could help researchers quickly pave the way for more clinical trials in asymptomatic patients. 

“Reducing the number of PET scans could enable us to conduct twice as many clinical trials for the same amount of time and money,” he said in a statement. “It’s not the $4,000 per PET scan that we’re worried about. It’s the millions of patients that are suffering while we don’t have a treatment. If we can run these trials faster, that will get us closer to ending this disease.”