The New Alzheimer’s Disease Test You Should Know About
New research finds a blood test accurately diagnoses Alzheimer’s disease in patients.
The blood test was 90% accurate in the study.
This blood test is currently available in the U.S.
Alzheimer’s disease impacts more than 6 million Americans, slowly destroying memory and thinking skills until people are unable to do even the simplest tasks. But the medical community has struggled be able to accurately diagnose the condition, and tests are often invasive. Now, new research has found that Alzheimer’s disease may be able to be accurately diagnosed with the help of a simple blood test.
The study, which was published in JAMA, analyzed data from about 1,200 people who sought care for mild memory problems. About 300 patients were given the blood test, known as amyloid probability score 2, or APS2. Their results were compared with results from spinal taps or PET scans.
The researchers also asked primary care doctors and memory specialists to determine based on evaluations which patients had Alzheimer’s disease. The researchers discovered that the primary care doctors were wrong in their Alzheimer’s disease diagnosis 36% of the time. They were also wrong 41% of the time when they thought patients didn’t have Alzheimer’s disease but actually did.
Memory specialists did a little better: They were wrong 25% of the time in giving patients an Alzheimer’s disease diagnosis and 29% of the time in missing a proper diagnosis.
But the blood test was only wrong 10% of the time.
Meet the experts: Verna Porter, M.D., a neurologist and director of the Dementia, Alzheimer’s Disease and Neurocognitive Disorders at Pacific Neuroscience Institute in Santa Monica, CA, Matthew Schrag, M.D., Ph.D., assistant professor of neurology at the Vanderbilt University School of Medicine; Michal Schnaider Beeri, Ph.D., director of the Herbert and Jacqueline Krieger Klein Alzheimer’s Research Center at Rutgers University.
So, how does the APS2 test work and why it is important? Neurologists explain.
What is the APS2 blood test for Alzheimer’s disease, and how does it work?
The APS2 blood test for Alzheimer’s disease is a blood test that’s sold under the name PrecivityAD2. It looks at several ratios for certain blood biomarkers in identifying Alzheimer’s disease—APS2 and p-tau217.
“By analyzing these biomarkers, the model calculates a score, known as the Amyloid Probability Score 2 (APS2), which ranges from 0 to 100,” explains Michal Schnaider Beeri, Ph.D., director of the Herbert and Jacqueline Krieger Klein Alzheimer’s Research Center at Rutgers University. “This score indicates the likelihood that a patient has amyloid plaques in their brain, which are the core pathology with Alzheimer’s disease.”
The test is currently available in the U.S., but there aren’t clinical guidelines for using it right now. Meaning, it’s not considered part of the standard way of diagnosing Alzheimer’s disease.
The test is done via a simple blood draw, and the sample is then shipped off to a lab for analysis. From there, doctors will get a positive or negative result that tells whether there is a high or low likelihood that someone has brain amyloids. Brain amyloids are proteins that clump together to form plaques in the brain and are a hallmark of Alzheimer’s disease, per the National Institute on Aging (NIA).
Who should get the APS2 blood test for Alzheimer’s disease?
Right now, there are no clear clinical guidelines to spell out how this test should be used. Also worth noting: The blood test wasn’t very accurate in the earliest stage of Alzheimer’s disease, and was highest when patients had dementia. So, there seems to be a sweet spot in using it.
Still, doctors say interest in the test is understandable. “This could significantly improve early diagnosis and patient management, ideally, providing earlier access to treatment,” says Verna Porter, M.D., a neurologist and director of the Dementia, Alzheimer’s Disease and Neurocognitive Disorders at Pacific Neuroscience Institute in Santa Monica, CA.
What is the most accurate diagnostic test for Alzheimer’s disease?
Doctors have a few different options for diagnosing Alzheimer’s disease, and that’s a big deal. “Over... 20 years or so, the single biggest success in Alzheimer’s disease is in how we diagnose it,” says Matthew Schrag, M.D., Ph.D., assistant professor of neurology at the Vanderbilt University School of Medicine. “Not long ago, Alzheimer’s disease was an autopsy diagnosis, which is not particularly practical.”
Now, Dr. Scrag says that doctors can get “excellent diagnostic results” using certain kinds of PET scans or by measuring cerebrospinal fluid. “But these types of PET scans are expensive and not available at most sites, and cerebrospinal fluid tests require a lumbar puncture,” he says. “Having a reliable blood test on the market would make the diagnostic process much easier.”
Dr. Scrag points out that this isn’t the only blood test for Alzheimer’s disease out there. “A number of blood tests are looking promising, and most are based on detecting forms of beta-amyloid and/or tau in the blood—the test in this paper uses both approaches,” he explains.
But while Dr. Scrag calls these study results “impressive,” he says people shouldn’t assume that it’s more reliable than a doctor. Why? “The results need to be interpreted in the context of patients’ symptoms,” he explains.
Dr. Porter says that more research is needed to see how best to use these tests in the future. “This includes assessing whether early and accurate diagnosis through blood tests leads to timely and appropriate treatment interventions, improved patient prognoses, and better overall healthcare efficiency,” she says.
This particular test was used on a sample group in Sweden and Dr. Scrag says it’s important to use it on different demographics in the future, along with making sure the findings can be replicated. “Nevertheless, this is a promising result and hopefully will be thoroughly validated and available in the clinic in the near future,” he says.
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