The third FDA-cleared Alzheimer's blood biomarker test is C2N Diagnostics' PrecivityAD2, cleared Aug. 20, 2026 for symptomatic adults as young as 40. Younger-onset families can compare options by age eligibility, what the test measures, proven accuracy, and how a clinician uses the result.
A blood biomarker test measures blood proteins linked to Alzheimer's brain changes, especially amyloid buildup. The earlier options were limited to adults 55 and older with cognitive symptoms. PrecivityAD2 opens testing to adults 40 and older with signs of cognitive impairment, 15 years younger than prior clearances.
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:
- Read the official guidance from Alz — Use this primary source to verify the official guidance.
- Read the official guidance from Brightfocus — Use this primary source to verify the official guidance.
Table of Contents
- Why does age 40 matter?
- What does PrecivityAD2 measure?
- How accurate was it?
- How do the cleared tests compare?
- What should families do next?
Why does age 40 matter?
Younger-onset Alzheimer's often brings memory, language, planning, or behavior changes during work and parenting years. The Alzheimer's Association reports that PrecivityAD2 is the first cleared test for symptomatic adults as young as 40 clearance announcement.
The test is intended for adults 40 and older with signs of cognitive impairment to help detect amyloid pathology. Amyloid pathology means abnormal amyloid protein buildup linked to Alzheimer's disease.
What does PrecivityAD2 measure?
PrecivityAD2 uses high-resolution mass spectrometry on a blood sample. Mass spectrometry is a lab method that identifies and measures tiny protein fragments by weight.
It measures plasma Aβ42/40 and p-tau217/np-tau217 ratios, then combines them in a proprietary multi-analyte score. A ratio compares two related protein levels to reveal a disease signal more clearly than one level alone.
How accurate was it?
In a 1,142-person study of people with symptoms, researchers compared blood results with PET scans or spinal-fluid tests. PET and spinal-fluid tests directly confirm amyloid in brain or fluid. According to the American Psychiatric Association's news alert, a positive PrecivityAD2 result had 97.6 percent positive predictive value and correctly ruled in 98 percent of amyloid-positive cases while confirming 93 percent of negatives test performance summary.
How do the cleared tests compare?
The BrightFocus Foundation notes that the two earlier clearances were Fujirebio's Lumipulse G pTau217/β-Amyloid 1-42 ratio in May 2025 and Roche's Elecsys pTau181 in Oct. 2025, both for adults 55 and older with symptoms test clearance history.
Families can scan these differences: Roche reports that its Aug. 24, 2026 Elecsys pTau217 test is the first single-biomarker, single-cutoff test supporting both rule-in and rule-out use in primary and specialty care product announcement.
- Fujirebio Lumipulse G pTau217/β-Amyloid 1-42 ratio — cleared May 2025, ages 55 and older with symptoms
- Roche Elecsys pTau181 — cleared Oct. 2025, ages 55 and older with symptoms
- C2N PrecivityAD2 — cleared Aug. 20, 2026, ages 40 and older with symptoms, multi-analyte score
- Roche/Eli Lilly Elecsys pTau217 — cleared Aug. 24, 2026, ages 55 and older, single-biomarker and single-cutoff design for rule-in and rule-out in primary and specialty care
What should families do next?
Cleared blood tests are adjuncts, not stand-alone diagnoses or screens for people without symptoms. A clinician must pair the result with history, exams, cognitive testing, and sometimes PET or spinal-fluid follow-up.
Bring a symptom timeline, medication list, sleep and mood history, and family history to the visit. Ask whether a blood biomarker test fits, which test the clinic offers, what a positive or negative result would change, and whether referral or confirmatory testing is needed.
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