BY TAMARA BHANDARI

Up to two decades before people develop the characteristic memory loss and confusion of Alzheimer’s disease, damaging clumps of protein start to build up in their brains. And there is growing consensus among neurologists that Alzheimer’s treatment needs to begin as early as possible, ideally before any cognitive symptoms arise. By the time people become forgetful, their brains are so severely damaged no therapy is likely to fully heal them.

A BLOOD TEST TO DETECT THE EARLY BRAIN CHANGES OF ALZHEIMER’S DISEASE HAS MOVED ONE STEP CLOSER TO REALITY.
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This current understanding of the nature of Alzheimer’s disease and its progression amplifies the already urgent need for Alzheimer’s treatments and the clinical trials—and qualified participants—needed to study then.

“Right now, we screen people for clinical trials with brain scans, which is time-consuming and expensive, and enrolling participants takes years,” says Randall Bateman, MD, Washington University neurologist at Barnes-Jewish Hospital and director of the Dominantly Inherited Alzheimer Network Trials Unit, also known as DIAN-TU.

But recently, researchers from Washington University School of Medicine reported that they can measure levels of the Alzheimer’s protein amyloid beta in the blood and use such levels to predict whether the protein has accumulated in the brain. When blood amyloid levels are combined with two other major Alzheimer’s risk factors—age and the presence of the genetic variant APOE4—people with early Alzheimer’s brain changes can be identified with 94% accuracy, the study found.

In short, a blood test to detect the early brain changes of Alzheimer’s disease has moved one step closer to clinical use.

Such a test may become available at doctors’ offices within a few years, but its benefits will be much greater once there are treatments to halt the disease process and forestall dementia. Clinical trials of preventive drugs have been hampered by the difficulty of identifying participants who have Alzheimer’s brain changes but no cognitive problems. A blood test could provide a way to efficiently screen for people who could participate in clinical trials.

“With a blood test, we could potentially screen thousands of people a month,” says Bateman “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.”

IF WE CAN RUN THESE TRIALS FASTER, THAT WILL GET US CLOSER TO ENDING THIS DISEASE.” — RANDALL BATEMAN, MD, NEUROLOGIST

As part of the study, researchers analyzed the enrollment process for a prominent Alzheimer’s prevention trial called the A4 study. This project used PET scans to confirm the presence of early Alzheimer’s brain changes in potential participants. Results showed that prescreening with a blood test—followed by a PET scan for confirmation—would have reduced the number of PET scans needed by two-thirds. Unlike blood tests, which cost a few hundred dollars, each PET scan costs upward of $4,000. A single research site can only run a few dozen such scans a month, because PET scanners are primarily reserved for patient care, not research studies.

“If you want to screen an asymptomatic population for a prevention trial, you would have to screen, say, 10,000 people just to get 1,500 or 2000 that would qualify,” Bateman says. “Reducing the number of PET scans could enable us to conduct twice as many clinical trials for the same amount of time and money. 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.”

Originally published by Washington University School of Medicine at medicine.wustl.edu/news