FDA greenlights first blood test to help diagnose Alzheimer’s disease in the US

The US Food and Drug Administration has given marketing clearance to a blood test to help diagnose Alzheimer’s disease, making the test the first to get signoff to aid in the early detection of the disease in the United States.

It works by measuring two proteins in blood plasma: pTau217 and beta-amyloid 1-42. A ratio of those proteins tends to correlate with the occurrence or absence of amyloid plaques in the brain, which are among the hallmarks of Alzheimer’s disease. The test does not measure amyloid directly but can signal its presence.

However, there remains no current single test to diagnose Alzheimer’s disease. Doctors primarily rely on a variety of tools to diagnose the condition, which may include medical history, neurological exams, cognitive and functional evaluations, brain imaging, spinal fluid analysis and, more recently, blood tests.

The FDA said the results of the newly cleared blood test must be assessed in conjunction with other clinical information from a patient