The FDA cleared PrecivityAD2, a blood test from C2N Diagnostics, on August 20, 2026, for adults aged 40 and older who show signs of cognitive impairment. That makes it the first FDA-cleared Alzheimer's blood test available to patients this young, which matters directly for families dealing with younger-onset Alzheimer's. Younger-onset Alzheimer's refers to the disease appearing before age 65. Until now, blood-based biomarker tests had been cleared only for older patients, leaving younger people to rely on more invasive or expensive options to get an amyloid-pathology answer.
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.
Table of Contents
- What PrecivityAD2 Actually Measures
- How Accurate Is the Test?
- Who the Test Is For — and Who It Isn't For
- What This Means for Getting a Diagnosis Sooner
- Where PrecivityAD2 Fits Among Other Blood Tests
- Frequently Asked Questions
What PrecivityAD2 Actually Measures
PrecivityAD2 uses high-resolution mass spectrometry to measure two ratios in blood plasma: the Aβ42/40 ratio and the p-tau217/np-tau217 ratio. The test combines these into a proprietary score and reports one of three results — negative, positive, or "likely positive" for amyloid pathology, according to NeurologyLive.
Amyloid pathology refers to the buildup of amyloid plaques in the brain, one of the hallmark changes associated with Alzheimer's disease. Measuring it in blood is what makes this test useful: it gives clinicians a biomarker reading without a PET scan or a spinal tap. It is the third blood-based Alzheimer's biomarker test the FDA has cleared, and the first cleared specifically for use starting at age 40, which is what extends its reach to people with younger-onset disease, per the Alzheimer's Association.
How Accurate Is the Test?
The clearance rested on a trial of 1,142 adults, in which PrecivityAD2 showed a 97.6% positive predictive value and a 93.1% negative predictive value when checked against amyloid PET or cerebrospinal fluid (CSF) testing. Those predictive values are comparable to the more invasive and expensive methods it's meant to supplement, according to the Alzheimer's Drug Discovery Foundation. Families should know these numbers describe the newer pivotal trial, not every study of PrecivityAD-family testing.
An earlier evidence review by Health Technology Wales reported sensitivity of 88%–90% and specificity of 89%–92% for the test family — lower figures that are worth keeping in mind when weighing confidence in any single result. That gap doesn't cancel out the newer numbers; it's a reminder that predictive value and sensitivity/specificity are different measurements, and that test performance can vary across study populations. A result from PrecivityAD2 is one data point for a clinician to weigh, not a standalone verdict.
Who the Test Is For — and Who It Isn't For
PrecivityAD2 is meant for adults 40 and older who are already showing signs or symptoms of cognitive impairment. It is explicitly not a standalone diagnostic or a screening tool for people without symptoms, and it's intended to be used alongside other clinical evaluation, not in place of one, per the Alzheimer's Association.
That distinction matters most for younger families. A person in their 40s or 50s with memory or thinking changes can now be offered this test as part of a workup that previously might have jumped straight to a PET scan or spinal tap. HealthDay described the clearance as giving clinicians a faster, less invasive option than those procedures for confirming amyloid pathology in symptomatic people, including those under 65, HealthDay reported.
- Eligible: age 40+, already showing cognitive symptoms, being evaluated by a clinician
- Not intended for: people with no symptoms seeking a screening test on their own
- Not a replacement for: a full clinical workup that includes history, cognitive testing, and a doctor's judgment
What This Means for Getting a Diagnosis Sooner
The practical benefit for younger-onset families is speed. The Alzheimer's Association's president said younger-onset Alzheimer's is a reality for many families, and this clearance may help them get diagnostic answers sooner than before, according to the Alzheimer's Association.
Getting an earlier, less invasive read on amyloid status can shorten the diagnostic process for people whose symptoms started well before the age ranges most testing has historically targeted. A blood draw is simpler to arrange than a PET scan or lumbar puncture, which can mean fewer appointments and less waiting for a working answer.
Where PrecivityAD2 Fits Among Other Blood Tests
PrecivityAD2 follows the FDA's earlier clearance of Fujirebio's Lumipulse blood test, placing it within a still-young but growing category of blood-based Alzheimer's diagnostics, per the Alzheimer's Drug Discovery Foundation. For a family navigating a younger-onset case, this means PrecivityAD2 is one option among a small but expanding set of blood-based tools, each cleared for somewhat different patient groups. Asking a clinician which test applies to a specific age and symptom picture is a reasonable next step, since clearance details differ by product and by age threshold.
Frequently Asked Questions
Does PrecivityAD2 diagnose Alzheimer's by itself?
No. It's intended to be used alongside other clinical evaluation in people already showing cognitive symptoms, not as a standalone diagnostic or a screening tool for people without symptoms.
How is PrecivityAD2 different from a PET scan or spinal tap?
It measures amyloid-related biomarkers from a blood draw instead of brain imaging or cerebrospinal fluid, offering clinicians a faster, less invasive way to check for amyloid pathology.
Is PrecivityAD2 the only blood test cleared for Alzheimer's?
No. It's the third blood-based Alzheimer's biomarker test the FDA has cleared, following Fujirebio's Lumipulse test, but it's the first cleared specifically for patients as young as 40.
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