By Alex Janin
For years, doctors relied only on written memory tests, invasive spinal taps and expensive imaging to diagnose Alzheimer's disease. Now, two Food and Drug Administration-cleared blood tests are simplifying the diagnosis.
The tests, from manufacturers Fujirebio Diagnostics and Roche Holding, were cleared last year and look for different versions of tau, a protein that forms into tangles in the brain and can lead to memory loss. Fujirebio's test also measures a protein called beta-amyloid, which can form sticky plaques that are a hallmark of Alzheimer's disease and the target of recently approved drugs for the condition.
These tests, which use different methods and report results in different ways, can help evaluate patients with early signs of cognitive decline, neurologists say, but they aren't designed to predict Alzheimer's risk in healthy people. Even if they could, there are no approved treatments to prevent the onset of the disease yet.
"Until there is a treatment for asymptomatic people, this will probably not be a routine health check," says Dr. Hyun-Sik Yang, a neurologist at Mass General Brigham and assistant professor at Harvard Medical School. "There's a tension about more knowledge versus, do you really need to know?"
Whether doctors want people to get these tests or not, the demand is there. Doctors say they are fielding more requests for these tests from healthy, symptom-free patients, many of whom have a family history of Alzheimer's or dementia. A 2025 survey from the Alzheimer's Association found that 91% of Americans would want to take a simple test, like a blood test, to know if they had the disease.
Consumers are increasingly seeking access to and knowledge about their own health. The proliferation of wearable devices, direct-to-consumer testing, and more personalized forms of care, such as concierge medicine, has made it easier to do so.
Alzheimer's-related testing, which generally requires a doctor's order, is just one slice of that. A blood test can be a lower-cost, less cumbersome option for people with signs of cognitive decline, and these tests may eventually prove helpful for people with a family history of Alzheimer's disease who want to know more about their risk. Drugmakers are also developing medications that target tau tangles in the brain so patients may have more options in the future.
Yang and other neurologists say some healthy patients have already found ways to get the tests, and come to them concerned when they see results suggesting signs of Alzheimer's may be present in the brain. He reassures them, noting that many healthy older adults have amyloid buildup but not all of them develop Alzheimer's disease.
Roughly 15% of healthy, symptom-free people already have abnormal levels of amyloid in their brains at age 50, according to a 2022 meta-analysis published in JAMA Neurology. By age 75, that number jumps to more than a third of people, and roughly half by age 85.
A baseline measure was what 34-year-old Patrick Murray was looking for. When he heard about a study at the Institute for Neurodegenerative Diseases of Florida that was using blood tests to evaluate personalized prevention plans for people with a family history of neurodegenerative diseases, he signed up.
There were no red flags in his test results, he says, but he still met with a nurse practitioner trained in preventive neurology in the hopes of optimizing his health. He made several lifestyle changes, including getting more consistent sleep, doing more Zone 2 exercise and eating more salmon for the omega-3 fatty acids.
Murray, a father of three who works in finance, plans to repeat the testing in the future to see whether the lifestyle changes made any impact.
"I wanted to be as aware and as prepared as I possibly can," he says. "I'm trying to do as much as I can to give myself a better chance to continue to live a long and healthy life."
Research into whether Alzheimer's tests and treatments can help prevent or delay the disease is accelerating. There is a growing body of evidence supporting certain behavioral changes to promote brain health, such as eating a healthy diet, not smoking, and limiting alcohol.
Pharmaceutical companies are studying whether Alzheimer's drugs on sale or in development could also slow or delay the onset of symptoms if given before they appear. Some of these trials are using blood tests to screen participants, making it easier for researchers to find people who qualify. Drugmakers like Eli Lilly as well as partners Biogen and Eisai are studying whether their amyloid-targeting drugs work to prevent the disease.
"It's not going to be reasonable to ask a population of people over 55 to all go and get fancy brain imaging tests and spinal taps," says Geoffrey Kerchner, the global head of neurodegeneration at Roche, which is also planning an Alzheimer's prevention trial for its experimental drug. "It's going to be reasonable for them to get it just as part of their general blood work."
Researchers are also studying whether finger-prick blood samples can pick up Alzheimer's-related signs as reliably as standard blood draws, which could make in-home testing for research a possibility. Early data suggest the samples are promising, but not ready for clinical use yet, says Nicholas Ashton, senior director of the fluid biomarker program at Banner Sun Health Research Institute and one of the study investigators.
Even in people with symptoms of cognitive decline, positive results on the FDA-cleared tests don't prove that a patient has Alzheimer's disease, neurologists caution. Further imaging and testing is required, says Dr. Arjun Masurkar, a cognitive neurologist and associate professor at NYU Grossman School of Medicine. The results on both tests can vary subject to daily body fluctuations, such as whether the patient is sick, he adds.
"Any acute inflammatory event could even temporarily alter the levels of these biomarkers," says Masurkar. "Even whether you've eaten a meal can affect it."
For the so-called "worried well," which could include people with or without a family risk, Masurkar recommends getting a baseline evaluation of their brain function, which often involves getting a brain MRI scan and doing a pencil-and-paper cognitive test. Insurance coverage for that kind of evaluation isn't guaranteed. But the results can serve as a benchmark that doctors can use to track a patient's health in subsequent years.
"Anything fancier than that is neither supported by evidence nor needed, " he said.
Write to Alex Janin at alex.janin@wsj.com
(END) Dow Jones Newswires
June 15, 2026 11:00 ET (15:00 GMT)
Copyright (c) 2026 Dow Jones & Company, Inc.
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