The FDA cleared C2N Diagnostics' PrecivityAD2 blood test for marketing on Aug. 19-20, 2026 as an Alzheimer's pathology assessment test.
For family caregivers, the news means doctors now have a cleared blood option for adults age 40 and older who already show signs of cognitive impairment. PrecivityAD2 is a blood test that measures Alzheimer's-related proteins to estimate the likelihood of brain amyloid buildup. It does not diagnose Alzheimer's alone and must be used alongside a clinical evaluation, according to the FDA clearance document the FDA clearance document.
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:
- Explore the official data from FDA — Use this primary source to review the underlying data.
- Read the official guidance from Washu — Use this primary source to verify the official guidance.
Table of Contents
- Who is the test for?
- How does the test work?
- How accurate are the results?
- What should caregivers do with a result?
- Which version will the clinic offer?
Who is the test for?
The cleared use is narrow. It is for adults age 40 and older who have signs or symptoms of cognitive impairment and are being evaluated for Alzheimer's or other decline. Washington University Source reports this makes it the first cleared blood test down to age 40 the university announcement. It is not for screening healthy people.
C2N and FDA labeling also state it is not a stand-alone diagnosis. A false positive can lead to the wrong treatment, while a false negative can delay needed care. Caregivers can use this distinction at appointments. If memory, thinking, language, or daily function has changed, bring specific examples and dates. If no symptoms exist, ask about other prevention and monitoring options instead.
How does the test work?
The test uses a standard blood draw. In the laboratory, it uses immunoprecipitation plus high-resolution liquid chromatography-tandem mass spectrometry to quantify plasma Aβ42, Aβ40 and p-tau217/np-tau217. Those results are combined into an Amyloid Probability Score 2.
The score reflects the likelihood that amyloid plaques linked to Alzheimer's are present in the brain. The doctor interprets that likelihood with memory testing, history, neurological examination, and other findings. For families, the practical difference is comfort and access. A blood draw offers a less invasive alternative to a brain amyloid PET scan or a spinal-tap spinal fluid test.
How accurate are the results?
In a 1,142-person symptomatic validation cohort checked against amyloid PET or cerebrospinal fluid, NeurologyLive reports positive results had 97.6% positive predictive value and negative results had 93.1% negative predictive value the NeurologyLive report. That means most positive and negative results matched the reference test. Uncertain results still happen.
About 17.3% of validation participants fell in an intermediate "likely positive" group where only 77.3% truly had amyloid. Caregivers should expect that some results will need follow-up testing or closer clinical follow-up. Performance held steady across 12 comorbidities including kidney disease, atrial fibrillation and diabetes. That matters because many older adults being evaluated have more than one health condition.
What should caregivers do with a result?
Do not treat a positive result as a final Alzheimer's diagnosis. Do not treat a negative result as proof that nothing needs attention. Keep follow-up appointments, track daily function, driving safety, finances, and home safety, and report changes.
- Bring a symptom timeline, medication list, and a second observer when possible.
- Ask what category the score falls in: negative, intermediate or positive.
- Ask whether the result changes the next step, such as referral, imaging, spinal fluid testing, or treatment eligibility.
- Ask how other causes of impairment, such as sleep apnea, depression, medication effects, or vascular disease, were considered.
Which version will the clinic offer?
The FDA-cleared kit version was expected to become available later in 2026, while C2N's existing CLIA laboratory-developed PrecivityAD2 test remained available. BrightFocus Foundation notes families may encounter either version during the transition the BrightFocus summary.
Ask directly whether the clinic offers the cleared or laboratory version. Also ask where the blood sample is sent, how long results take, what the result categories mean at that clinic, and what follow-up is planned for an intermediate result.
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