As recently as the spring of 2025, the Food and Drug Administration had not cleared a single blood test to help detect Alzheimer's disease. Today there are four. The first was cleared on May 16, 2025, and from a sample drawn from your arm it can help flag the sticky amyloid plaques tied to the disease.
Before these tests, confirming amyloid in a living person meant a positron emission tomography brain scan, whose first approved tracer dates only to 2012, or a spinal tap. Some laboratories had offered their own blood tests earlier, but none carried FDA clearance.
This matters to many families. The Alzheimer's Association reported in 2025 that more than 7 million Americans age 65 and older were living with the disease, and a test from the crook of the arm raises fair, practical questions that deserve plain answers.
What a Blood Test Can Now See
Alzheimer's disease shows up in the brain as two proteins behaving badly. One is amyloid, which clumps into plaques between nerve cells. The other is tau, which twists into tangles inside them.
Until recently, measuring these changes meant a positron emission tomography scan or a sample of spinal fluid. The new blood tests work differently, and they do not all measure the same thing.
Three of the four look at a form of tau called p-tau217, short for tau phosphorylated at position 217 on the protein. The fourth, Roche's Elecsys pTau181, measures a related form called p-tau181.
Both are versions of phosphorylated tau that rise as Alzheimer's changes take hold, and the number simply marks the spot on the protein. Researchers have found that p-tau217 tends to climb earlier and track amyloid buildup more closely, which is why it anchors most of the cleared tests.
Some tests also measure a piece of amyloid called beta-amyloid 1-42 and report a ratio. Whichever marker is used, a doctor reads the result alongside your history and a memory exam, the way a cholesterol number guides but does not replace a full heart evaluation.
Four Cleared Tests, and When They Were Cleared
The pace has been striking, and the dates worth noting are the ones on the FDA's clearance letters, which usually arrive a few days before a company's public announcement. On May 16, 2025, the FDA cleared the first blood test, made by Fujirebio, which reports the ratio of p-tau217 to beta-amyloid 1-42.
On October 8, 2025, the agency cleared a second test, Roche's Elecsys pTau181, the first blood test authorized for a primary care office to help rule out Alzheimer's-related amyloid. Roche announced that clearance on October 13.
Then, on a single day, August 19, 2026, the FDA cleared two more at once. One was C2N Diagnostics' PrecivityAD2, which uses mass spectrometry to measure both an amyloid ratio and a tau ratio.
The other was Roche's Elecsys pTau217, a single-biomarker test. The companies announced them on different days, C2N around August 20 and Roche on August 24, which is why some reports make them sound days apart.
But the clearance date for both was the same. That makes four cleared tests in about fifteen months, and cleared tools are now reaching ordinary doctors' offices, not only research centers.
Rule In, Rule Out, and What the Numbers Mean
The accuracy of these tests is strong but not simple, and the details matter. In the study behind the first cleared test, 91.7 percent of people with a positive result truly had amyloid confirmed by a brain scan or spinal fluid, and 97.3 percent with a negative result truly had none.
Fewer than 20 percent of samples came back indeterminate, meaning the result was unclear and more testing was needed. The Roche pTau181 test is often described by one figure, a 97.9 percent negative predictive value in its 312-person primary care study.
That means among people who got a negative result, nearly 98 in 100 were truly free of amyloid. But the same study showed a positive predictive value of only 22.4 percent.
In that low-prevalence setting, where about 13 percent of people actually had amyloid, most positive results were false alarms. That is by design. The pTau181 test is built to rule Alzheimer's out, not to rule it in, so a positive result there means little on its own and calls for further evaluation.
No single number tells the whole story, so a careful doctor pairs any result with everything else known about you.
Who the Tests Are For, and Who They Are Not
This is the point most often misunderstood, so it is worth stating plainly. The FDA cleared each of these tests only for adults who already show signs or symptoms of cognitive decline, such as memory trouble that family members notice or that interferes with daily life.
The age ranges differ. The Fujirebio Lumipulse test is cleared for symptomatic adults age 50 and older in a specialized care setting. Both Roche tests, the pTau181 and the pTau217, are cleared for adults age 55 and older.
The PrecivityAD2 test reaches the furthest, cleared for symptomatic adults as young as 40, which recognizes that younger-onset Alzheimer's is a real burden for some families. So two of the four, Lumipulse at 50 and PrecivityAD2 at 40, are cleared below age 55.
None of these tests was cleared as a screening tool for healthy people with no symptoms. In a person with no symptoms, a positive result does not reliably predict whether or when dementia will develop, and it can cause needless fear.
These are not do-it-yourself kits either. A physician must order the test and interpret the result. If you or someone you love is noticing real changes in memory, the first step is a conversation with a doctor.
A Recall Worth Knowing About
One safety matter deserves a plain mention, and it is narrow, not a reason to distrust the whole field. In December 2025, Fujirebio sent an urgent product correction to laboratories about specific lots of its Lumipulse test materials.
The FDA lists this as an open Class II recall, the middle of three tiers. The problem is that certain reagent and calibrator lots can produce falsely elevated ratios, which can push a result into the positive or indeterminate range when amyloid may not actually be present.
The affected cartridge lots are numbered D4C6028U, D4C6029U, D4C6051U, and D4C6052U, along with a few named calibrator lots, and the notice covered units sent to thirteen states. The test itself was not pulled from the market.
Laboratories were simply told to stop using the named lots. If you had a Lumipulse test in late 2025 or 2026 and received any result from those lots, it is fair to ask your doctor whether an affected lot was involved.
The FDA's notice directs laboratories and their medical directors to determine the appropriate action for results already generated, so how to read any result tied to an affected lot is best worked out between the laboratory and your treating clinician.
The Cost and the Insurance Picture
Price and coverage remain the rough edges, and a list price is not the same as your bill. C2N has listed its PrecivityAD2 test at about 1,450 dollars, and the company says it offers patient assistance to those who qualify, though that can still leave a sizable cost.
Fujirebio's Lumipulse test has not carried a firm public price and has been estimated to run between 500 and 1,000 dollars. Roche has not published a public list price for its cleared tests, so what you would owe there depends on the laboratory and the plan.
A separate blood test that is not among the four FDA-cleared ones, AD-Detect, was listed near 399 dollars. Coverage is starting to move. In July 2026, C2N announced that beginning October 1, 2026, eligible members of Anthem Blue Cross and Blue Shield would be the first in the country to have the PrecivityAD2 test covered under a medical policy, when a clinician deems it medically necessary.
That is a meaningful first, though it does not cover everyone. Medicare and many private plans have not settled their coverage, so do not assume any single test will be paid for.
Before any blood draw, ask what your specific plan will pay and what you would owe if it pays nothing.
Why Knowing Can Help, and What You Can Do
Some readers ask why anyone would want to know. There are solid reasons. Memory problems have many causes that can be treated, including low vitamin B12, an underactive thyroid, depression, poor sleep, and certain medications, so ruling out Alzheimer's helps a doctor look for a reversible problem.
A newer class of treatments can slow early decline, but only once amyloid is confirmed. And an early, accurate answer gives families time to arrange affairs and support while the person can still take part.
Your daily habits also shape the years ahead. In 2024 the Lancet Commission on dementia reported that nearly 45 percent of cases could potentially be prevented or delayed by addressing 14 risk factors.
Two were added that year, high LDL cholesterol, tied to about 7 percent of cases, and untreated vision loss, about 2 percent. The commission stressed that these steps matter across the whole of life, not one window alone.
Keep blood pressure controlled, treat hearing loss, stay active, avoid smoking, limit alcohol, manage blood sugar and weight, stay connected, and keep learning. Some of this calls for a doctor's help and a lab test, since checking cholesterol or blood sugar means drawing blood.
FDA-Cleared Blood Tests for Alzheimer's Disease, 2025 to 2026 (FDA clearance letter dates)
| Test | Maker | FDA cleared | Indication and main use |
|---|---|---|---|
| Lumipulse G pTau217 / beta-amyloid 1-42 plasma ratio | Fujirebio | May 16, 2025 | First cleared test; aids identifying amyloid; symptomatic adults 50 and older in specialized care |
| Elecsys pTau181 plasma | Roche | October 8, 2025 | First cleared for primary care to help rule out amyloid; symptomatic adults 55 and older |
| PrecivityAD2 (plasma amyloid and tau ratios by mass spectrometry) | C2N Diagnostics | August 19, 2026 | Reaches the youngest; cleared for symptomatic adults as young as 40 |
| Elecsys pTau217 single-biomarker plasma | Roche | August 19, 2026 | Single-biomarker test supporting both rule-in and rule-out across primary and specialty care; symptomatic adults 55 and older |
If memory changes are worrying you or your family, the sensible first move has not changed. See a doctor, describe what you have noticed, and ask for a full evaluation. A blood test can now be part of that workup, and it is a real advance, but treat the result as one piece of information rather than a verdict.
Ask what your plan will cover before any draw, ask what a positive or negative result would change in your care, and if you had a Lumipulse test recently, ask your doctor and the laboratory whether an affected lot was involved and how your result should be read. Meanwhile, tend to the habits that protect the brain, from blood pressure to hearing, vision, and staying active.
Weigh those steps with your doctor rather than assuming they are free of cost or trade-offs.
Sources
- Food and Drug Administration, FDA Clears First Blood Test Used in Diagnosing Alzheimer's Disease, FDA News Release (2025)
- Roche Diagnostics, Elecsys pTau181 Becomes the Only FDA-Cleared Blood Test for Use in Primary Care to Rule Out Alzheimer's-Related Amyloid Pathology (2025)
- C2N Diagnostics, Anthem Establishes Coverage of C2N Diagnostics' PrecivityAD2 Blood Test for Alzheimer's Disease Evaluation (2026)
- Food and Drug Administration, Class 2 Device Recall: Lumipulse G pTau217/Beta-Amyloid 1-42 Plasma Ratio, FDA Medical Device Recall Database (2026)
- Ritchie G et al., Elecsys pT181p Immunoassay: Clinical Performance for Ruling Out Amyloid Pathology, Alzheimer's and Dementia: Diagnosis, Assessment and Disease Monitoring (2026)
- Livingston G et al., Dementia Prevention, Intervention, and Care: 2024 Report of the Lancet Standing Commission, The Lancet (2024)