For decades, the only way to confirm that someone had Alzheimer’s disease was by autopsy after death, when pathologists could confirm amyloid plaques, which are hallmarks of the disease, in the brain. Doctors now use a combination of factors to diagnose Alzheimer’s, including reports from patients and their caregivers about changes in memory or other cognitive functions, performance on cognitive tests, brain imaging, and tests of spinal fluid. But some of these measures can be subjective, invasive, expensive, or hard to assess.
There are now four blood tests cleared by the U.S. Food and Drug Administration (FDA) to detect the earliest signs of the neurodegenerative disease: an important advance in helping to diagnose Alzheimer’s in more people, as well as detecting it earlier in the disease course. Eric Reiman, CEO emeritus and lead researcher at the Banner Alzheimer’s Institute in Phoenix.
Food and Drug Administration (FDA) in August make blood tests for Alzheimer's disease more widely available for doctors to prescribe—and in a younger population of people—for the first time. But that doesn't mean everyone should get one. Here's what to know about the available blood tests for Alzheimer's disease and when experts recommend taking them.
The first blood test for the disease, made by Fujirebio, was cleared by the FDA in May 2025. It determines the ratio of two key Alzheimer’s proteins—a form of beta amyloid and a form of tau—which reflects whether amyloid plaques are accumulating in the brain. But the test can only be run on specialized equipment and therefore isn't widely available in commercial labs.
The second test, made by Roche and FDA-cleared in October 2025, detects levels of a version of tau that correlates with the buildup of amyloid plaques. It's the first Alzheimer’s blood test that primary care physicians can prescribe to rule out the disease. The latest two tests, cleared in August, are intended to make diagnosing Alzheimer’s disease easier and more accurate.
PrecivityAD2, a new blood test from the diagnostics company C2N, is based on an earlier version of the company's test that was available only via certified labs. It uses a technology called mass spectrometry that is a more sophisticated way of picking up amyloid and tau compared to traditional assays. It provides a probability score that reflects how likely a person is to have amyloid plaques in the brain.
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