PrecivityAD2 can now be used in symptomatic adults as young as 40, giving doctors a blood draw instead to check for amyloid plaques.
For decades, confirming Alzheimer’s disease meant one of two things: a PET scan that could cost thousands of dollars and involve radioactive tracers, or a spinal tap that plenty of patients simply refused. Both are accurate. Both are also, understandably, a hard sell to someone who’s already frightened about their memory.
That bottleneck just got smaller. The US Food and Drug Administration (FDA) cleared C2N Diagnostics’ PrecivityAD2 test, a blood test that can now be used, alongside a standard clinical workup, to help identify brain amyloid pathology in adults 40 and older who are showing signs of cognitive decline [1].
What sets this clearance apart is that C2N’s Precivity tests have existed for a while as lab-developed tools. It’s the age range. PrecivityAD2 is now the only FDA-cleared test authorized for symptomatic adults starting at 40, more than two decades younger than when most people think to worry about Alzheimer’s. That range matters because the disease doesn’t wait for a diagnosis criteria to catch up with it.
An estimated 19 to 20 million Americans 65 and older live with cognitive impairment, and hundreds of thousands more are struggling with it between 45 and 65 – an age bracket where doctors are far less likely to reach for dementia testing in the first place.
In a validation study of 1,142 people showing signs of cognitive decline, the test’s positive results correctly predicted amyloid pathology 97.6% of the time, and its negative results correctly ruled it out 93.1% of the time, when checked against PET scans or spinal fluid testing. A third category, “likely positive,” showed up in about 17% of subjects and still carried a 77% predictive value, giving physicians a clearer next step even in the murkier cases rather than a flat yes-or-no.
The science behind those numbers is genuinely clever, even if the acronyms aren’t: the test uses high-resolution mass spectrometry to measure two blood-based signals, a ratio of amyloid proteins and a ratio of tau proteins, and combines them into a single score. Think of it less like a single dial and more like triangulating a location from two separate readings; each one narrows things down, and together they land somewhere far more precise than either could alone.
One detail is easy to skim past but matters enormously in practice: the test’s accuracy stayed consistent across 12 chronic conditions common in older adults, including atrial fibrillation, chronic kidney disease, diabetes, high blood pressure and a history of stroke. Blood tests can be thrown off by exactly this kind of comorbidity; it’s a large part of why earlier biomarker efforts struggled to reach the clinic. A test that performs reliably in someone who’s also managing three or four other age-related conditions is a test that’s actually usable in the real population it’s meant to serve, not just a pristine trial cohort.
Dr Joel Braunstein, C2N’s co-founder, CEO and president, called the clearance “a watershed moment for our company, the entire Alzheimer’s disease community, the field of molecular diagnostics and precision medicine,” adding that the company believes the test “will play a vital health system role in the years ahead to help streamline and simplify the complex diagnostic pathway that many patients face when dealing with serious memory concerns.”
That pathway has real stakes attached to it now that anti-amyloid drugs exist. Getting an answer sooner means getting to treatment sooner, and treatment windows for these therapies are narrow; they work best early, before too much damage has accumulated. A test that removes the friction of a PET scan referral or a spinal tap could be the difference between a patient starting treatment months earlier or not starting at all.
The bigger arc: catching decline before it defines a decade. Alzheimer’s has always sat at an uncomfortable edge of the longevity conversation; extending years of life means little if cognition doesn’t come along for the ride. A blood test that can flag amyloid pathology in a routine visit, rather than after months of specialist referrals, shifts brain health screening closer to where cardiovascular and metabolic screening already sit: something checked early, checked often and acted on while there’s still room to change the trajectory.
The FDA-cleared version is expected to reach clinics later this year, while the current CLIA-validated version remains available now.
[1] https://c2n.com/news-releases/bg2ziqcz39o3wxf5uc04u279ziw0yv
