Before people begin to experience common symptoms like memory loss, the medical community has struggled to diagnose Alzheimer’s disease. Now, a new blood test may be able to identify markers of Alzheimer’s up to two decades before those symptoms arise, an initial study from Washington University School of Medicine shows.

In pre-clinical trials, the test has proven 94% accurate, researchers said.

The blood test measures levels of amyloid beta, a protein fragment that builds up in the brain to create the plaques and tangles characteristic of Alzheimer’s.

The levels of this protein, when combined with other risk factors, can identify people with early Alzheimer’s brain changes — long before it affects cognition.

To improve the blood test’s accuracy, researchers combined the results with several risk factors for Alzheimer’s, including age, gender, and genetic disposition in their analysis.

The risk of developing the disease doubles every five years for people over the age of 65, women are two-thirds more likely to have the disease, and the genetic variant APOE4 increases someone’s risk anywhere from three to five times.

Researchers said this new blood test may be even better than the current standard — a PET brain scan — at detecting early amyloid deposits in the brain.

The test is still in the initial phase and is not yet available to the public. However, researchers are hopeful that within a few years, it will pass clinical trials and receive government clearance for doctors to use.

“[W]ith a blood test, we could potentially screen thousands of people a month.”
Randall J. Bateman, MD
Washington University School of Medicine

Earlier diagnosis also raises the prospect of more effective treatment. Once there is a test that more accurately identifies people with early Alzheimer’s, other studies can be done on ways to halt the disease’s progression.

“Right now, we screen people for clinical trials with brain scans, which is time-consuming and expensive, and enrolling participants takes years,” said senior author Randall J. Bateman, MD, the Charles F. and Joanne Knight Distinguished Professor of Neurology. “But with a blood test, we could potentially screen thousands of people a month.”

As Bateman notes, “That means we can more efficiently enroll participants in clinical trials, which will help us find treatments faster, and could have an enormous impact on the cost of the disease as well as the human suffering that goes with it.”

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