Blood test could predict Alzheimer's disease years before symptoms appear, study by Boston researchers finds

A new study finds that a simple blood test could predict Alzheimer's disease long before symptoms appear.

Harvard University-affiliated researchers at Mass General Brigham in Boston say that the test for pTau217, an amyloid protein that build plaques in the brain linked to Alzheimer's, "has the potential to predict progression of the illness years before symptoms or brain scan changes."

A blood test is much simpler than a spinal tap or PET scan, researchers said.

"We used to think that PET scan detection was the earliest sign of Alzheimer's disease progression, revealing amyloid accumulation in the brain 10 to 20 years before symptoms appear," lead study author Hyun-Sik Yang, a Harvard Medical School assistant professor of neurology, said in a statement. "But now we are seeing that pTau217 can be detected years earlier, well before clear abnormalities appear on amyloid PET scans."

Last year, the Food and Drug Administration gave marketing approval to the first blood test to help doctors diagnose Alzheimer's in some patients. 

The Harvard study followed 317 adults with healthy brains who were between 50 and 90 years old. Participants underwent blood tests for pTau217, as well as PET scans and cognitive testing. 

"Researchers found that higher levels of pTau217 predicted a faster buildup of Alzheimer's disease pathology, even when initial brain scans appeared normal," Mass General Brigham said.

The researchers aren't recommending this blood test for all older adults yet, but they hope it could one day be used for "routine health maintenance."

"By anticipating who's going to turn amyloid-positive in the future, we are trying to push back the clock to enable earlier Alzheimer's disease prediction," Mass General Brigham neurologist Dr. Jasmeer Chhatwal said.  

Last year, a Harvard Medical School study found that lithium could one day help treat Alzheimer's.