Key takeaways:
It can be difficult to diagnose Alzheimer’s disease. There’s no single test that can diagnose it, and its symptoms can overlap with other conditions.
New blood tests measure levels of proteins in the blood, which are higher in people with Alzheimer’s. The FDA recently cleared two of these tests for people age 55 and older who show signs of the disease.
Current research suggests these blood tests may help diagnose people with Alzheimer’s more quickly and more accurately than current tests.
Alzheimer’s disease is a common condition in the U.S. More than 1 in 9 adults over the age of 65 have it.
People with Alzheimer’s may have trouble with memory, making decisions, and handling daily tasks. But these symptoms can easily be confused with normal age-related memory changes. Because of this, it can be difficult to diagnose this condition, especially in its earlier stages.
Fortunately, scientists have developed new blood tests for Alzheimer’s disease that may help detect the condition sooner.
What are the new blood tests for Alzheimer’s disease?
In 2025, the FDA cleared two blood tests to assist with Alzheimer’s disease diagnosis:
The first test is called the Lumipulse G pTau217/ß-Amyloid 1-42 Plasma Ratio test. It measures two proteins (pTau217 and β-amyloid 1-42) in your blood. These proteins are typically higher in people with Alzheimer’s. The test calculates the ratio of these proteins, which is linked to the presence or absence of amyloid plaques in your brain. Amyloid plaques are a hallmark sign of Alzheimer’s disease.
The second blood test is called the Elecsys pTau181. It measures a protein called phosphorylated Tau (pTau) 181 in your blood. This protein is also linked to amyloid plaques in your brain.
Both tests are for people ages 55 years and older who have signs and symptoms of Alzheimer’s disease. They aren’t screening tests for people without symptoms.
What’s the difference between the tests?
The available blood tests for Alzheimer’s disease measure different proteins in your blood. Another big difference is where the tests are available. The Lumipulse test is limited to specialty clinics, while primary care physicians can order or administer the Elecsys test.
How is Alzheimer’s disease diagnosed?
Blood tests for Alzheimer’s disease are relatively new. Before going over the specifics, it helps to understand how Alzheimer’s is usually diagnosed.
Diagnosis often starts by looking at a person’s symptoms. Early symptoms of Alzheimer’s can be hard to spot. It can also be hard to accept the possibility that you or someone you know may have it. Family and friends often notice changes first.
In addition to memory loss, people with Alzheimer’s may also experience:
Trouble following directions
Forgetting where they are
Problems with language
Changes in mood
Spending more time alone
Trouble managing finances
Difficulty with planning
If your loved one has symptoms of dementia, their primary care provider can perform a series of tests that can help figure out if they could have Alzheimer’s. These include:
Cognitive tests: These usually include a series of questions and tasks to help evaluate thinking.
Blood and urine tests: These tests can help rule out other conditions, like electrolyte imbalance or a urinary tract infection (UTI), which can cause confusion in older adults.
Imaging tests of the brain: Brain imaging can help rule out other causes of the symptoms.
These test results can provide important information about your health. But it can still be hard to know for sure if someone has Alzheimer’s. There’s no single test that can diagnose Alzheimer’s with 100% certainty, so healthcare professionals use other tests to help.
How do the blood tests for Alzheimer’s work?
Alzheimer’s disease is caused by changes in the way cells in your brain talk to each other. Scientists believe that abnormal levels of proteins — called beta-amyloid and tau — cause this to happen. Everyone has these proteins in their body, but people with Alzheimer’s often have higher levels.
There are a few tests that healthcare professionals can use to measure levels of these proteins:
Lumbar puncture: This is often referred to as a spinal tap. It’s a procedure that uses a thin needle to collect a sample of fluid from around the spinal cord.
PET scan: This is an imaging technique that scans your brain. It’s similar to getting an MRI.
Blood test: This is a new way of measuring the levels of certain proteins in your blood.
The blood test is a faster, easier way to measure these proteins. Spinal taps and PET scans are a bit more involved. And they can’t be performed in a regular doctor’s office. This can also delay the time it takes to get results.
Why is this test important?
Having blood tests for Alzheimer’s disease is important for a few reasons:
They’re easier for people to access than PET scans or lumbar punctures.
They’re also cheaper and provide faster results.
They’re less invasive than a lumbar puncture.
They make it easier for researchers to monitor people in clinical trials.
Scientists hope these new blood tests can be used to diagnose Alzheimer’s disease earlier and more quickly than current methods. An earlier diagnosis means Alzheimer’s can be treated sooner. It may also help researchers discover new therapies.
How accurate is blood testing for Alzheimer’s disease?
Any test used to diagnose a medical condition, including Alzheimer’s disease, needs to be accurate to make sure the diagnosis is reliable.
A clinical study looked at the Lumipulse blood test in over 1,000 older adults. The blood test detected Alzheimer’s disease with about 90% accuracy, which is very high. In comparison, standard methods used to diagnose Alzheimer’s are about 60% to 70% accurate. Since these other tests are less accurate, they may miss a diagnosis.
For FDA approval, experts reviewed a different set of data for the Lumipulse blood test. They reported high accuracy, at almost 92%. Negative results were confirmed in 97% of cases, meaning the test has a low probability of missing the disease when it’s present. About 20% of test results were inconclusive.
Results from the clinical study involving the Elecsys test haven’t been published yet. But according to the manufacturer, the Elecsys pTau181 test correctly ruled out Alzheimer’s disease 97.9% of the time in a clinical trial with 312 participants.
What does it mean if the test is positive or negative?
For someone with symptoms of Alzheimer’s, a positive test likely means they have the condition. A negative test indicates that Alzheimer’s is unlikely, but it doesn’t rule it out entirely.
A primary care provider or dementia specialist will use the test results in combination with other factors (as noted above) to make a diagnosis. They can help you and your loved one determine the best next steps after the blood test.
Frequently asked questions
Blood tests for Alzheimer’s disease can be performed at some outpatient offices and most large commercial laboratories. You’ll need a doctor’s order for the test before you go.
Because these tests are new, it’s best to check with your healthcare team or the lab before committing to the test. There’s no official policy yet regarding Medicare coverage, but legislation is pending.
The Self-Administered Gerocognitive Examination (SAGE) test isn’t a diagnostic test. But it allows you to assess your own thinking abilities and catch any memory problems. The test takes about 15 minutes and is available in a digital version or on paper. You can take it anytime or anywhere, on your own, or with your primary care provider.
Blood tests for Alzheimer’s disease can be performed at some outpatient offices and most large commercial laboratories. You’ll need a doctor’s order for the test before you go.
Because these tests are new, it’s best to check with your healthcare team or the lab before committing to the test. There’s no official policy yet regarding Medicare coverage, but legislation is pending.
The Self-Administered Gerocognitive Examination (SAGE) test isn’t a diagnostic test. But it allows you to assess your own thinking abilities and catch any memory problems. The test takes about 15 minutes and is available in a digital version or on paper. You can take it anytime or anywhere, on your own, or with your primary care provider.
The bottom line
For many years, scientists have worked hard to find a test that can accurately diagnose Alzheimer’s disease. The FDA has cleared two new blood tests that can help detect Alzheimer’s more quickly and accurately than previous methods. But these tests aren’t for everyone. Your healthcare team will likely use a blood test as part of their diagnostic process. Experts expect that the new tests will help people with Alzheimer’s start treatment earlier and improve research on treatments.
Why trust our experts?
References
Alzheimer’s Association. (n.d.). Alzheimer’s disease facts and figures.
Fischer Center for Alzheimer’s Research Foundation. (2025). FDA approves new blood test for Alzheimer’s.
Fisher Center for Alzheimer’s Research Foundation. (2025). What to know about the new blood test for Alzheimer’s.
National Institute on Aging. (2024). What happens to the brain in Alzheimer’s disease? National Institutes of Health.
Palmqvist, S., et al. (2024). Blood biomarkers to detect Alzheimer disease in primary care and secondary care. JAMA.
Roche Diagnostics. (n.d.). Roche’s Elecsys® pTau181 becomes the only FDA-cleared blood test for use in primary care to rule out Alzheimer’s-related amyloid pathology.
Wexner Medical Center. (n.d.). SAGE: A test to detect signs of Alzheimer’s and dementia.
U.S. Food and Drug Administration. (2025). FDA clears first blood test used in diagnosing Alzheimer’s disease.
Olinger, H. (2025). Bipartisan lawmakers introduce bill to expand Medicare coverage for Alzheimer’s screening. WVVA.
