In 2026, the FDA cleared PrecivityAD2, a blood test that estimates the likelihood of brain amyloid pathology in symptomatic adults. The main changes were its regulatory status and eligibility starting at age 40; the test had already been clinically available in another form. The clearance does not make PrecivityAD2 the first FDA-cleared Alzheimer's blood test. The FDA gave that distinction to Fujirebio's Lumipulse test in May 2025 for symptomatic adults 55 and older, according to the FDA's first-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:
- Read the official notice from FDA — Use this primary source to verify the official announcement.
- Explore the official data from FDA — Use this primary source to review the underlying data.
Table of Contents
- What did the FDA clearance change?
- Who is the cleared test for?
- What does PrecivityAD2 measure?
- How strong is the reported evidence?
- What should patients and families do next?
What did the FDA clearance change?
The FDA's device database lists C2N Diagnostics' PrecivityAD2 under 510(k) number K253240. It classifies the test as a "substantially equivalent" Class II device for assessing amyloid pathology, as shown in the FDA's PrecivityAD2 record. The documented action is FDA clearance, so calling the test "FDA-approved" would be imprecise. PrecivityAD2 was not new to clinical practice.
before clearance, clinicians could order it as a CLIA-validated laboratory-developed test, or LDT. An LDT is developed and performed within a clinical laboratory rather than sold as the newly cleared in vitro diagnostic version. C2N said on August 20, 2026, that the orderable test remained the LDT and that the FDA-cleared version was expected later in 2026. Therefore, a PrecivityAD2 result issued around the clearance date did not automatically come from the cleared device.
Who is the cleared test for?
The cleared use covers adults 40 or older who have symptoms of cognitive impairment and are being evaluated for Alzheimer's disease or another cause of cognitive decline. This extends below C2N's previous clinical-test positioning for people 50 or older.
Age alone does not make someone an appropriate candidate. PrecivityAD2 is not cleared as routine screening for people without cognitive symptoms, and a result is not a stand-alone Alzheimer's diagnosis. The practical eligibility questions are: The Alzheimer's Association advises using blood biomarkers after a comprehensive evaluation in specialized cognitive care, as described in its blood-biomarker clinical guidance.
- Is the person at least 40?
- Are cognitive symptoms present?
- Is a clinician evaluating those symptoms?
- Will the result be interpreted as part of that evaluation?
What does PrecivityAD2 measure?
PrecivityAD2 measures two biomarker ratios in blood plasma using high-resolution mass spectrometry. One compares amyloid-beta 42 with amyloid-beta 40, written as Aβ42/40. The other compares phosphorylated tau 217 with non-phosphorylated tau 217.
The test combines those measurements into an Amyloid Probability Score 2 ranging from 0 to 100. The score indicates how likely it is that amyloid pathology is present in the brain. Amyloid pathology can support an Alzheimer's evaluation, but the score does not independently identify the complete cause of a person's symptoms. A clinician must interpret it alongside the broader clinical assessment.
How strong is the reported evidence?
C2N reported a validation study involving 1,142 symptomatic people. Researchers compared PrecivityAD2 with amyloid PET visual readings or cerebrospinal-fluid biomarkers, according to C2N's FDA-clearance announcement. Among results classified as positive under the study's dual-cutoff approach, the positive predictive value was 97.6%.
That means 97.6% of those positive results agreed with an amyloid-positive reference finding. Negative results had a 93.1% negative predictive value, meaning 93.1% agreed with an amyloid-negative reference finding. These figures are not the same as overall accuracy, and they are not guarantees for every patient. They describe positive and negative results in a symptomatic validation population under the reported study conditions.
What should patients and families do next?
Someone considering PrecivityAD2 should begin with an evaluation of the cognitive symptoms rather than seeking the test as general screening. The ordering clinician should explain what question the result could answer and how it would affect the next decision. Before testing, ask: Before the blood draw, ask the clinician or laboratory to identify which PrecivityAD2 version will appear on the test report.
- Is this the FDA-cleared in vitro diagnostic or the CLIA-validated LDT?
- How will the result be combined with the clinical evaluation?
- What would a positive or negative result mean in this person's case?
- What additional evaluation might be needed if the result does not resolve the uncertainty?
