The FDA cleared C2N Diagnostics' PrecivityAD2 blood test on Aug. 20, 2026 to help evaluate Alzheimer's in symptomatic adults age 40 and older.
For younger-onset families, the comparison turns on age cutoff, accuracy for amyloid, and where the test runs. PrecivityAD2 is a blood test that helps clinicians identify brain amyloid pathology, the plaque buildup linked to Alzheimer's. According to the Alzheimer's Association, the clearance covers symptomatic adults from age 40 in a clinic evaluation (clearance announcement).
Medical information disclaimer: This article is for general educational purposes only and does not provide medical advice, diagnosis, or treatment. Always consult a physician or other qualified health professional about symptoms, medications, tests, or treatment decisions.
Official resources:
- Check eligibility on C2N’s official study page — Use this page to check the study’s participation requirements.
- Read the official guidance from Alz — Use this primary source to verify the official guidance.
Table of Contents
- What does PrecivityAD2 measure?
- How accurate is a positive result?
- How do the new options compare by age?
- What does access look like in practice?
- What should families ask before testing?
What does PrecivityAD2 measure?
The test uses high-resolution mass spectrometry to measure plasma Aβ42/40 and percent p-tau217 ratios. It combines them into an Amyloid Probability Score 2 from 0 to 100. A higher score signals higher likelihood of brain amyloid.
The score aids evaluation, but it does not alone diagnose Alzheimer's. According to C2N Diagnostics, the test must be used with clinical assessment by an experienced provider, not as screening or a stand-alone diagnosis (company announcement). Families should expect history, thinking tests, and exam alongside blood work.
How accurate is a positive result?
In a 1,142-person symptomatic validation study, a positive PrecivityAD2 correctly ruled in amyloid in about 98% of cases confirmed by PET or spinal fluid testing. The American Psychiatric Association's Psych News reported that finding in September 2026 (Psych News report). That strength matters when travel to PET centers is hard.
A strong rule-in result can focus next steps. Accuracy still depends on correct use. Symptoms must be present, the sample must be handled properly, and the clinician must fit the result to the person.
How do the new options compare by age?
PrecivityAD2 was the third FDA-cleared Alzheimer's blood test, after Fujirebio Lumipulse in May 2025 and Roche Elecsys pTau181 in October 2025. It was the first cleared below age 55.
Days later the FDA also cleared Roche's Elecsys Phospho-Tau 217P Plasma test with Eli Lilly for symptomatic adults 55 and older to detect amyloid pathology. That leaves a clear age split for younger-onset concerns. For families comparing choices, check these points:.
- Age at symptom visit: 40-plus points to PrecivityAD2, 55-plus opens both options
- Care setting: memory clinic, neurology, or primary care with dementia experience
- Test path: central lab draw and shipping versus local hospital instrument
- Follow-up plan: how a positive, negative, or borderline score changes referrals and counseling
What does access look like in practice?
For younger-onset families, the practical difference is access. According to ALZFORUM, PrecivityAD2 covers symptomatic adults from age 40 via a central St. Louis lab, while Roche's test runs on about 4,500 distributed instruments but starts at 55 (ALZFORUM comparison).
A central lab can mean a blood draw near home plus shipping and waiting. A distributed instrument can mean faster local processing where available. Neither path removes the need for counseling. Ask who will explain results, document the plan, and support work and family decisions.
What should families ask before testing?
Confirm that symptoms are documented and that the ordering clinician manages dementia evaluations. Ask about medicines, other brain conditions, and recent illness that could shape interpretation. Ask how results return, what score ranges trigger PET, spinal fluid testing, or specialist referral.
Ask whether genetic counseling is offered when onset is early and family history is strong. Neither test is approved for asymptomatic screening, and families should not seek testing for worried relatives without symptoms. Plan one visit for consent and draw, and a second visit for results with a support person present.
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