Alzheimer's Blood Tests: FDA Clears Two More, Raising Total to Four

Two clearances within a week

In late August 2026, the U.S. Food and Drug Administration cleared two more blood tests that help doctors check for the brain changes linked to Alzheimer's disease. That brings the number of FDA-cleared Alzheimer's blood tests to four, all within about 15 months.17 C2N Diagnostics' PrecivityAD2 was cleared on August 20. Roche's Elecsys Phospho-Tau (217P) Plasma test, which Roche developed with Eli Lilly, followed on August 24.7 The Alzheimer's Association called the Roche test the fourth such clearance and the second in a single week.11

Many headlines said the FDA "approved" these tests. In regulatory terms, that is not quite right, and the difference matters to anyone following FDA decisions on drugs and devices. The official term is "cleared," which is the language used by the companies, the Alzheimer's Association and most trade outlets.1113 The first test in the group, Fujirebio's Lumipulse assay, was reviewed under the agency's Breakthrough Device program. That program is meant to speed up review of devices that could improve diagnosis or treatment of life-threatening or irreversibly debilitating conditions.20 One FDA document for the earlier Roche pTau181 assay is labeled a 510(k) decision summary, a review pathway for devices.19 So this is a device story, not a drug approval. Even so, as discussed below, it is closely tied to the market for Alzheimer's drugs.

What each new test does

The two new tests are built differently. PrecivityAD2 combines the amyloid-beta 42/40 ratio and a p-tau217 ratio into an algorithm called the amyloid probability score 2 (APS2).5 It is the first FDA-cleared Alzheimer's blood test for symptomatic adults as young as 40.4 In a validation study of 1,142 people with cognitive symptoms, it had a positive predictive value of 97.6% and a negative predictive value of 93.1% when checked against amyloid PET scans or spinal-fluid biomarkers.1 An FDA-cleared version is expected later in 2026. In the meantime, C2N sells a laboratory-developed version under CLIA rules, the federal standards for clinical labs.1

Roche's test measures a single protein, phosphorylated tau 217. Roche describes it as the only FDA-cleared single-biomarker blood test that can help both confirm and rule out amyloid pathology, using the same cutoffs in primary and specialty care.13 Results come back as positive, intermediate or negative.13 One comparison puts its positive and negative predictive values at 96.6% and 92.5%.7 It is cleared for adults 55 and older with signs, symptoms or complaints of cognitive decline.12

Roche's biggest advantage may be practical. The test runs on the company's installed base of more than 4,500 cobas laboratory instruments in the U.S., so labs need no new equipment.13 Labcorp and Quest Diagnostics have both said they plan to offer it.1516 Roche has not said what it will cost.15 The European clearance came first, in May.16

How fast the field has moved

All four tests are cleared only for people who already have cognitive symptoms. They serve different purposes:

• Lumipulse G (Fujirebio): cleared May 16, 2025, used mainly to confirm amyloid pathology in specialty settings.
• Elecsys pTau181 (Roche): cleared in October 2025, used mainly to rule out Alzheimer's pathology in primary care.
• PrecivityAD2 and Elecsys pTau217: both can help confirm or rule out amyloid pathology.7

Isobel Coleman, CEO of the Alzheimer's Drug Discovery Foundation, pointed out that just over a year earlier, no Alzheimer's blood test had FDA clearance.4 Before the Lumipulse decision, the only ways to confirm amyloid plaques in a living patient were a PET scan or a spinal tap.7 One market overview put PET scans at $5,000 to $8,000. It said list prices for blood assays ranged from roughly $250 to $1,200.17 Those figures come from a single secondary source and should be treated as rough.

The tests also appear to help doctors outside neurology. A study presented at the 2026 Alzheimer's Association International Conference looked at 1,310 patients evaluated by 165 physicians. After seeing PrecivityAD2 results, primary care doctors' diagnostic accuracy rose from 65% to 93%.4

Why drugmakers care: the treatment link

The main reason these clearances matter to the drug industry is the Alzheimer's treatment pipeline. Lilly's role in the Roche test is a clear sign of that. Carole Ho, who leads Lilly Neuroscience, said the partnership aimed to put one test into primary care, where most patients with memory complaints are first seen.13 CNN described the clearance as part of a race among drugmakers and diagnostics companies to build simpler tests as demand grows for earlier diagnosis and treatment.16 One industry overview links plasma p-tau217 testing directly to deciding which patients can receive the anti-amyloid drug lecanemab.17

The reasoning is simple, though the coverage rarely spells it out. Anti-amyloid drugs only make sense for patients who have amyloid in the brain. Confirming that has required costly scans or spinal taps that are hard to get, which limits how many patients can be found for treatment. A blood test that can run in thousands of existing hospital labs removes much of that bottleneck. Randall Bateman of WashU Medicine, who co-developed the research behind PrecivityAD2, put it plainly: faster diagnosis lets patients start treatment earlier, when it works best.4

The labeling, however, sets clear limits. Roche says the safety and effectiveness of its assay have not been established for predicting who will develop dementia or for monitoring how a patient responds to therapy.13 That second point is important. For now, the test can help decide who might be eligible for a drug, but it is not cleared to track whether the drug is working. Some clinicians already use p-tau217 and amyloid blood tests informally to follow patients' responses to treatment and lifestyle changes.16 That practice goes beyond what the FDA has signed off on.

Payment is the other open question. One overview reports that the Centers for Medicare & Medicaid Services (CMS) has started work on reimbursement for FDA-cleared plasma Alzheimer's biomarkers. It says a national coverage determination is expected in late 2026.17 If that happens, it may do more to shape real-world use than the clearances themselves.

Where the coverage agrees and where it differs

The coverage agrees on the main warnings. No cleared test is meant to screen healthy people, and none is a stand-alone diagnosis.1712 Harvard neurologist Rachel Buckley said blood tests should not be used in people without symptoms until there is a disease-modifying therapy for that group.16 Clinicians also warn about false positives. They note that sample handling problems, kidney disease or viral illness can make results harder to read.16

Some coverage overstates the news. One Korean medical column described the August clearance as an early diagnostic test.8 The labels say the tests aid in identifying amyloid pathology in people who already have symptoms, which is narrower.13 Reports also differ on some details. Sources give different clearance dates for the pTau181 assay (October 8 vs. October 13, 2025) and different minimum ages for the Lumipulse test (50 vs. 55).71920 Readers should check the official labeling rather than rely on summaries.

The PrecivityAD2 age expansion deserves the most caution. Internist Dung Trinh notes that amyloid pathology is less common in younger adults. That lowers the chance of disease before testing and makes results harder to interpret.1 One outlet adds that validation groups for people in their 40s are still fairly small. It also notes that a positive result at that age can affect work, family and financial planning, so careful counseling before testing is essential.5

The Lumipulse test's history is a reminder that clearance is not the end of the story. The FDA posted a Class II recall for certain Lumipulse reagent lots in February 2026, after reports that they could produce falsely high ratios.19 That recall had little attention in the August coverage, but it shows that quality control after launch matters as much as accuracy data before launch.

Bottom line

This looks like the point where Alzheimer's blood testing moves from specialist clinics into routine care. The Roche test fits into lab equipment hospitals already own, and Labcorp and Quest have committed to offering it.15 C2N's lower age limit opens testing to a group that has long waited years for a diagnosis.3

The bigger effect will likely be on how drugs reach patients. Cheaper, faster amyloid testing directly expands the number of patients who can be identified for anti-amyloid therapies. That helps explain why a major drugmaker co-developed one of these tests. The limits are still real: the tests cannot predict dementia in healthy people, are not cleared to monitor treatment, and need clinical judgment to interpret. These clearances solve an access problem, but they are not a screening tool for the general public.