FDA Clears Third Alzheimer's Blood Test, This One for Patients as Young as 40

The FDA cleared C2N Diagnostics' PrecivityAD2 blood test on Thursday, August 20. It's the third Alzheimer's blood test cleared by the agency in about a year, and the first one approved for patients as young as 40, according to C2N's own announcement and MedPage Today.

That age threshold matters. Alzheimer's biology can start building in the brain 15 to 20 years before symptoms show up, according to the Alzheimer's Drug Discovery Foundation (ADDF). Until now, blood tests cleared by the FDA targeted older patients. Fujirebio's Lumipulse test, cleared in May 2025, was limited to adults 50 and older in specialized-care settings, according to Los Altos Neurology. PrecivityAD2 pushes that floor down a full decade.

What the test actually does

PrecivityAD2 isn't a screening test you can order on a whim. It's meant for adults 40 and older who already have signs or symptoms of cognitive decline and are being evaluated by a healthcare professional, according to C2N's press release and confirmed by MedPage Today. The company is explicit that it's not a standalone diagnostic and not for screening people with no symptoms.

The test uses high-resolution mass spectrometry to measure two blood biomarkers: the ratio of phosphorylated tau 217 to non-phosphorylated tau, and the amyloid-beta 42/40 ratio. Those combine into a score called the amyloid probability score 2, or APS2, which runs 0 to 100 and estimates the likelihood a patient has amyloid plaques, a hallmark of Alzheimer's, according to Medical Device Network.

In a validation study of 1,142 people with cognitive symptoms, the test hit a 97.6% positive predictive value for ruling in amyloid pathology and a 93.1% negative predictive value for ruling it out, measured against amyloid PET scans or cerebrospinal fluid testing, according to C2N and independently reported by MedPage Today, BioSpace, and CLP Magazine. C2N also reported the test held up consistently across 12 chronic conditions common in older patients, including diabetes, kidney disease, and depression.

C2N CEO Dr. Joel Braunstein called the clearance "a watershed moment for our company, the entire Alzheimer's disease community, the field of molecular diagnostics, and precision medicine," according to Medical Device Network.

A crowded, fast-moving field

This is the third FDA-cleared Alzheimer's blood test in roughly a year, which is a genuinely fast pace for a diagnostic category that had zero cleared blood tests until 2025. Isobel Coleman, CEO of the ADDF, which has funded C2N's research for nearly two decades including a $7 million investment through its Diagnostics Accelerator, said "just over a year ago, there were no FDA-cleared blood tests for Alzheimer's and now we have three," according to a PRNewswire release from the ADDF.

The ADDF has an obvious financial and reputational stake in touting this as validation of its funding strategy, and its statement reads more like a victory lap than neutral analysis. That doesn't make the underlying FDA clearance or the validation-study numbers false, but readers should note the ADDF is not a disinterested observer here.

The catch: these tests aren't magic, and one already got recalled

Fujirebio's Lumipulse test, the one cleared in May 2025 for patients 50 and up, is currently under an FDA Class II recall. According to Los Altos Neurology, the FDA posted the recall after reports that specific Lumipulse lots produced falsely elevated ratios, leading to excessive positive or indeterminate results and reduced accuracy compared to PET scans or spinal fluid testing. As of early August 2026, that recall remains active in the FDA's database.

Anyone tempted to treat these blood tests as a substitute for a doctor's full workup should consider this a caution. A young, fast-moving diagnostic category with three different companies racing to market is exactly the kind of environment where manufacturing or calibration problems can slip through. The Lumipulse recall demonstrates the risk is real.

C2N and every source covering PrecivityAD2 are careful to repeat that this test is meant to be used "in conjunction with clinical assessment," not as a replacement for it. A positive or negative blood result still needs to be read by a healthcare professional experienced in cognitive evaluation, alongside a patient's history, function, and other testing.

What's next

The FDA-cleared version of PrecivityAD2 is expected to be available later this year, according to C2N. Until then, a CLIA-validated version remains available through the company's own lab. GlobalData projects the Alzheimer's diagnostics and treatment market will grow at a 21.8% compound annual rate across eight major markets, reaching $33 billion by 2033, according to Medical Device Network. This suggests more competitors and more blood tests are coming. Whether the FDA's clearance pace can keep up with quality control, given the Lumipulse recall, remains to be seen.