FDA Clears Four Alzheimer's Blood Tests as Simpler Diagnosis Enters Primary Care

Two new blood tests for Alzheimer's disease cleared federal review in August, and the wave is drawing as much scrutiny as it is enthusiasm. The tests, C2N Diagnostics' PrecivityAD2 and Roche's Elecsys pTau217, developed in collaboration with Eli Lilly, bring the number of FDA-cleared blood-based Alzheimer's tests to four, according to a review of FDA clearance documents and reporting by Medical News Today.

The story that matters most to patients isn't the regulatory count. It's who these tests are actually for, and what a positive result actually means once it leaves the lab.

Start with the age question. PrecivityAD2 is the first FDA-cleared Alzheimer's blood test indicated for symptomatic adults ages 40 and older, according to a press release issued by C2N Diagnostics on August 20. Roche's Elecsys pTau217 is cleared for patients 55 and older with signs, symptoms, or complaints of cognitive decline, as stated in a Roche announcement on August 24.

That lower age floor matters, because amyloid plaques, the brain protein deposits the tests are designed to detect, can accumulate decades before any memory loss appears. A 42-year-old worried about word-finding problems is a very different clinical picture than a 70-year-old who's failing her clock-drawing test. Neither group should walk away from a blood result without a specialist conversation, and that's the part of the pipeline that still isn't built.

Both clearances come with a limit that deserves to be read closely. As reported by Medical News Today on September 26, neither test should be interpreted as a stand-alone diagnosis of Alzheimer's disease. Roche's Elecsys pTau217, in particular, uses two validated cutoffs and includes an intermediate category that, per the clinical review published by NeurologyLive, requires further testing to confirm amyloid pathology.

What the tests do measure is phosphorylated tau 217, or pTau217, a protein biomarker that neurologists at Harvard Medical School have described as strongly predicting amyloid plaque buildup in the brain, as cited in CNN's reporting on the clearances. That's a meaningful signal. It isn't a diagnosis.

For primary care physicians, that distinction is the operational problem. Traditionally, diagnosing Alzheimer's required expensive and invasive procedures like PET scans or spinal taps, as CNN noted. Now a family medicine doctor can order a blood draw, get a result in roughly 18 minutes on Roche's cobas system, and be left to explain what amyloid pathology means to a patient who came in asking whether their forgetting is normal aging or something worse.

The access piece is real. Labcorp and Quest Diagnostics have both announced plans to carry Roche's Elecsys pTau217 through their networks, with Quest expecting to introduce a lab service based on the assay in the fourth quarter of 2026, according to reporting by ACNR. More than 4,500 compatible Roche analyzers are already installed across U.S. labs.

Access isn't the same as readiness, though. A blood test that's available everywhere is only useful if the clinician ordering it knows what to do when the result comes back intermediate, or positive, or positive in a 44-year-old without clear specialty-care follow-up options in her county.

The C2N press release, reviewed via BusinessWire, estimates that 19 to 20 million U.S. adults 65 and older, plus hundreds of thousands more between 45 and 65, are living with cognitive impairment and may benefit from an earlier diagnosis. That's the population these tests are designed to reach. The clinical infrastructure to counsel and triage that population hasn't expanded at anything like the same pace.

None of that is an argument against the clearances. A simpler, less invasive way to assess amyloid pathology is a real clinical advance, and for patients waiting months for a neurology appointment, a clearer picture earlier is not nothing, it's the difference between qualifying for a treatment trial or missing the window.

But read the indication language carefully: these tests are cleared for use alongside clinical assessment, by clinicians experienced in evaluating cognitive impairment. The practical question for health systems right now is who, exactly, that describes in an era of specialist shortages, and what happens to patients whose primary care doctors order these tests without a neurologist or geriatrician in the referral chain.

Sources cited:
- Medical News Today (https://www.medicalnewstoday.com/articles/fda-clears-two-new-alzheimers-blood-tests-including-one-for-adults-as-young-as-40)
- C2N Diagnostics press release via BusinessWire (https://secure.businesswire.com/news/home/20260820868989/en/FDA-Clears-C2N-Diagnostics-PrecivityAD2-First-Alzheimers-Blood-Test-for-Adults-with-Cognitive-Symptoms-as-Young-as-40)
- Roche press release via PR Newswire (https://www.prnewswire.com/news-releases/roche-receives-fda-clearance-for-elecsys-ptau217-advancing-alzheimers-disease-assessment-across-primary-and-specialty-care-302857619.html)
- NeurologyLive (https://www.neurologylive.com/view/fda-clears-roche-single-biomarker-elecsys-ptau217-blood-test-alzheimers)
- ACNR (https://acnr.co.uk/elecsys-ptau217-blood-test-alzheimers/)
- CNN (https://www.cnn.com/2026/08/24/health/alzheimers-blood-test-fda)
- Alzheimer's Association (https://www.alz.org/news/2026/fda-clearance-elecsys-ptau217-blood-test-alzheimers)