FDA Clears First-of-Its-Kind Alzheimer Blood Test for Adults With Cognitive Symptoms

The US Food and Drug Administration has cleared C2N Diagnostics’ PrecivityAD2 blood test to aid in the evaluation of Alzheimer disease in adults aged 40 years and older who present with signs or symptoms of cognitive impairment, according to a company announcement.

PrecivityAD2 is the first FDA-cleared Alzheimer blood test for adults aged 40 years and older with cognitive symptoms, according to the press release. The FDA-cleared version of the test is expected to become available later this year; the current CLIA-validated PrecivityAD2 test remains available through C2N’s clinical laboratory.

The test is intended for use in conjunction with clinical assessment to help health care professionals experienced in the evaluation of cognitive impairment identify patients with amyloid pathology associated with Alzheimer disease. It is not intended for use as a screening test or as a stand-alone diagnostic test.

How does the PrecivityAD2 test work?

PrecivityAD2 uses high-resolution mass spectrometry to measure plasma beta-amyloid and tau peptide isoforms in blood. Specifically, the test quantifies the Aβ42/40 ratio and the p-tau217/np-tau217 ratio, also referred to as %p-tau217.

Those 2 ratios are then combined into a proprietary statistical algorithm to calculate the amyloid probability score 2, or APS2, which ranges from 0 to 100 and is intended to indicate the likelihood of amyloid pathology associated with Alzheimer disease.

C2N stated that PrecivityAD2 is the first FDA-cleared test powered by high-resolution mass spectrometry and a multiple analyte algorithm score for aiding diagnosis.

What performance data supported clearance?

In a clinical validation study of 1142 participants with signs or symptoms of cognitive decline, PrecivityAD2 used dual cutoffs to detect brain amyloid plaques, with performance assessed against amyloid PET visual read or cerebrospinal fluid biomarker testing.

A positive PrecivityAD2 result had a 97.6% positive predictive value for ruling in amyloid pathology, and a negative result had a 93.1% negative predictive value for ruling out amyloid pathology, according to C2N. A “likely positive” result occurred in 17.3% of participants and had a 77.3% positive predictive value.

The company stated that the test was effective at detecting amyloid plaques across the spectrum of cognitive impairment evaluated in the clinical study, including patients with mild symptoms and those with more advanced cognitive concerns.

C2N also reported consistent diagnostic performance with increasing age and across 12 prespecified chronic diseases associated with aging, including atrial fibrillation, autoimmune or inflammatory disease, chronic heart failure, chronic kidney disease, coronary heart disease, depression, diabetes, dyslipidemia, history of cancer, history of stroke or transient ischemic attack, hypertension, and obesity.

Why is this relevant to primary care?

Cognitive concerns often first arise in primary care, where clinicians may need to distinguish normal aging, depression, medication effects, sleep disorders, vascular cognitive impairment, Alzheimer disease, and other causes of cognitive decline. A blood-based biomarker test may help support earlier diagnostic workup and more timely referral or treatment planning for appropriate patients.

The clearance is also clinically relevant because access to amyloid PET imaging or cerebrospinal fluid testing may be limited by availability, cost, patient preference, or procedural burden. C2N positioned PrecivityAD2 as a scalable blood-based option to help identify amyloid pathology and guide next steps in the diagnostic care pathway.

Still, the test should be interpreted within the full clinical context. For primary care clinicians, the key practical distinction is that PrecivityAD2 is intended for symptomatic adults undergoing evaluation, not for population screening or diagnosis in isolation. Results should be integrated with cognitive assessment, medical history, medication review, functional evaluation, and consideration of alternative or contributing causes of impairment.

“FDA clearance is a watershed moment for our company, the entire Alzheimer’s disease community, the field of molecular diagnostics, and precision medicine,” Joel Braunstein, MD, MBA, cofounder, chief executive officer, and president of C2N Diagnostics, said in the announcement.

Reference

1. C2N Diagnostics. FDA clears C2N Diagnostics’ PrecivityAD2 — first Alzheimer’s blood test for adults with cognitive symptoms as young as 40. News release. Published August 20, 2026. Accessed August 21, 2026. https://precivityad.com/news/fda-clears-c2n-diagnostics-precivityad2-first-alzheimers-blood-test-for-adults-with-cognitive-symptoms-as-young-as-40nbsp