FDA clears Alzheimer's blood test for adults as young as 40

C2N Diagnostics' PrecivityAD2 becomes the first FDA-cleared blood test for Alzheimer's biomarkers reaching symptomatic patients in their 40s, pushing the diagnostic category's age floor 15 years below prior clearances.

The U.S. Food and Drug Administration cleared C2N Diagnostics' PrecivityAD2 blood test on August 20, 2026, for use in adults 40 and older who present with signs or symptoms of cognitive impairment, making it the first FDA-cleared Alzheimer's blood test to reach patients that young, according to the company's news release and a statement from the Alzheimer's Association.

PrecivityAD2 uses high-resolution mass spectrometry to measure two ratios from a blood draw, amyloid beta 42/40 and phosphorylated tau217 to non-phosphorylated tau217, combining them into what the company calls an Amyloid Probability Score. In C2N's clearance-supporting study of 1,142 symptomatic adults, a positive result carried a 97.6 percent positive predictive value and a negative result carried a 93.1 percent negative predictive value for amyloid pathology, measured against amyloid PET scans or cerebrospinal fluid testing, the company's release states. An intermediate "likely positive" result, which occurred in 17.3 percent of participants, carried a lower, 77.3 percent positive predictive value.

The clearance follows the FDA's May 2025 authorization of Fujirebio's Lumipulse test for adults 55 and older, and moves the cleared age floor for blood-based amyloid testing down by 15 years, according to trade coverage of the decision. "Just over a year ago, there were no FDA-cleared blood tests for Alzheimer's, and now we have three," said Isobel Coleman, chief executive of the Alzheimer's Drug Discovery Foundation, whose Diagnostics Accelerator had invested in C2N's underlying science.

The clearance itself carries a narrower label than the headline suggests. A summary of the decision published by CAP Today states the test is intended to be used alongside a clinical assessment by health care professionals experienced in evaluating cognitive impairment, and is not intended as a screening or stand-alone diagnostic test. The Alzheimer's Association made the same point in its own statement, noting that no single test, including this one, diagnoses Alzheimer's disease by itself.

The FDA-cleared version of PrecivityAD2 is expected to reach clinics later this year, C2N said in its release; the company's laboratory-run version of the test has been available under separate CLIA validation since 2023.