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What to Know About Blood Tests for Alzheimer’s Disease
Doctors say the tests could help people with symptoms get answers sooner
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For older adults experiencing memory loss or changes in thinking, getting or ruling out an Alzheimer’s diagnosis has long been a complicated process involving a patchwork of tests and screenings. But new blood tests are offering doctors a faster, less invasive way to spot signs of the disease that affects more than 7 million Americans.
Two blood tests that can help diagnose Alzheimer’s disease have been cleared by the Food and Drug Administration (FDA), and several more are being studied. Experts say the tests are not screening tools, meaning they are not for people who have no symptoms of dementia, and they are not intended to provide a definitive diagnosis. Rather, they can help improve the diagnostic process and prevent unnecessary testing in people who are unlikely to have the disease.
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Here’s what you need to know.
How the tests work
The tests look for markers of Alzheimer’s disease in a blood sample. These markers can include amyloid and tau — two proteins that are hallmarks of Alzheimer’s — along with other indicators of the disease.
Both FDA-cleared tests — Elecsys pTau181 and Lumipulse — detect the presence of amyloid plaques, abnormal clumps of protein in the brain that disrupt brain cell function.
PET scans and spinal fluid tests can also detect amyloid plaques and have been the standard of care for years to help doctors diagnose Alzheimer’s. But the tests are expensive and, in the case of a lumbar puncture (a.k.a. spinal tap), invasive. They can also be inaccessible for people in rural areas.
Blood tests, on the other hand, require only a blood draw.
“Having a blood test just makes it so much easier … to make a diagnosis of Alzheimer’s disease,” says Dr. Charles Bernick, a neurologist with the Cleveland Clinic Lou Ruvo Center for Brain Health in Las Vegas.
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The Elecsys pTau181 test is specifically designed for the primary care setting to help doctors rule out Alzheimer’s in patients who may exhibit symptoms of cognitive decline but are unlikely to have Alzheimer’s.
Using the tool in a primary care setting can help people at risk be referred to an appropriate specialist, while helping those not at risk identify other possible causes of their symptoms, explains Joanne Pike, Alzheimer’s Association president and chief executive officer.
“This approach also empowers primary care clinicians to guide referrals more effectively, allowing specialists to focus on patients most likely to require advanced evaluation and care,” Pike said in a news release.
While the Elecsys pTau181 test helps rule out Alzheimer’s disease, the Lumipulse lets doctors know if signs of the brain disorder are present. It’s intended for use in specialized care settings and for patients exhibiting signs and symptoms of cognitive decline.
Both tests check for proteins specific to Alzheimer’s disease; they can’t help diagnose other types of dementia, such as vascular dementia and Lewy body dementia.
There are other Alzheimer’s blood tests available in doctors’ offices and specialty clinics that have not been cleared by the FDA. Federal approval is not required for laboratory-developed tests such as these blood tests. Having the agency’s sign-off, however, confirms a test’s accuracy and opens the door for insurance coverage and more widespread use.
People without symptoms shouldn’t test
The newly approved blood tests are meant only for older adults who are experiencing symptoms of Alzheimer’s. And the FDA says blood test results should be used in conjunction with “other clinical evaluations or additional tests” to determine treatment options.
In addition to brain imaging and lumbar punctures, doctors often use neurological exams and cognitive tests, among others, to diagnose a patient with Alzheimer’s. “It still becomes a diagnosis where you have to really look at the whole picture,” Bernick says.
In recent years, the FDA has approved two medications for the treatment of Alzheimer’s — Kisunla (donanemab) and Leqembi (lecanemab). These drugs don’t cure the disease but may help to slow the rate of decline in people experiencing its early stages. (Researchers are still studying how much benefit the drugs provide over time, and some have questioned their effectiveness.) Because these drugs work by clearing amyloid plaques from the brain, the presence of amyloid must be confirmed before the drugs can be prescribed.
“They carry some risk. So if you’re going to use them ... you’ve got to be pretty sure the person has that protein in the brain,” Bernick says.
Risks can include swelling and bleeding in the brain.
Planning can be another reason to take the test if you have symptoms of Alzheimer’s disease. A clearer diagnosis can help families prepare for what’s ahead — from arranging caregiving support to reviewing benefits and finances.
Working to spot the disease earlier
While FDA-cleared tests are meant for people experiencing symptoms of dementia, scientists are studying tests that can detect the disease years before symptoms appear.
Research presented at the 2026 Alzheimer’s Association International Conference and published in JAMA found that cognitively healthy adults with high levels of p-tau217 — a marker associated with both amyloid and tau — had an approximately 78 percent risk of developing cognitive impairment, a precursor to Alzheimer’s, over 10 years. Even people with slightly elevated levels of p-tau217 in their blood had a risk of developing cognitive impairment, the researchers found.
“Once verified, these blood tests could be used to recruit patients for clinical trials of treatments to prevent cognitive decline and dementia. In the future, when treatments are approved for use early in the disease process, these tests could help guide monitoring, treatment decisions and counseling for patients and families,” says Rachel F. Buckley, lead author on the study and associate chair of research at the Mass General Brigham Neuroscience Institute in Boston.
Revolutionizing research and clinical care
Dr. Howard Fillit, cofounder and chief science officer of the Alzheimer’s Drug Discovery Foundation, says there’s been a “tremendous need” for blood tests and that having them more readily available will “revolutionize clinical care and clinical research” for Alzheimer’s.
“It’s going to reduce the cost of care and diagnosis, and it’s going to give people the opportunity to get a definitive diagnosis and enter into clinical trials,” Fillit told AARP.
He predicts that we’ll see more blood tests in the near future, including those that detect other key features of Alzheimer’s, such as inflammation in the brain. Having such tests could help doctors tailor a patient’s treatment as more medications come online.
“It’s kind of going to look like cancer, where patients have a tumor, there’s a biopsy of the tumor, the tumor cells are taken to the lab, they’re characterized according to various biomarkers, and then a treatment plan with various drugs in combination is designed for the patient, and the patient receives multiple drugs affecting multiple pathways in the cancer cell,” Fillit says.
“We’re going to have that for Alzheimer’s disease in the future. So this is just the beginning of really going into a new age of Alzheimer’s disease diagnosis and care and clinical trials.”
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