What to know about the new Alzheimer’s blood test

In May, the Food and Drug Administration gave the green light to a new blood test for Alzheimer’s disease that researchers say helps physicians diagnose the progressive neurological disorder earlier and at a lower cost.

It is the first FDA-cleared in vitro diagnostic test to identify patients with amyloid plaques associated with the disease in adults aged 50 years and older and exhibiting signs and symptoms of the disease, according to its manufacturer, Fujirebio Diagnostics.

There are several laboratory-developed tests on the market that can be used to detect blood-based biomarkers associated with Alzheimer’s. However, this is the first approved by the FDA.

The Lumipulse G pTau 217/β-Amyloid 1-42 Plasma Ratio test measures two proteins — pTau217 and β-amyloid 1-42, both found in human plasma — and calculates the numerical ratio of the levels of the two proteins. This ratio is correlated to the presence or absence of amyloid plaques in the patient’s brain, reducing the need for a PET scan. The test accurately predicted presence of amyloid plaque in a multi-center clinical trial with 92% accuracy.

Why this matters

Currently, physicians must take a detailed medical history, conduct cognitive testing, PET or MRI scans and take a sample of cerebrospinal fluid to accurately determine whether a person has amyloid-beta and tau proteins in their blood. These proteins can form decades before a person becomes symptomatic, making it extremely difficult to diagnose someone at the very earliest, or pre-clinical stage of Alzheimer’s disease, when existing treatment might be most effective. This new test only requires a simple blood draw, making it less invasive and much easier for patients to access.

For many years, blood tests have been used in clinical trials. Increasingly, they are being used by specialists in clinical settings, often as an initial tool prior to more testing. However, existing blood biomarker tests can present challenges, including setting accuracy standards, physician education, and use in diverse populations, according to The Lancet. While some commercial blood tests for Alzheimer’s are available, they are less accurate, less specific, less sensitive, and can be prone to false positives or negatives, according to University of Colorado behavioral neurologist Tara Carlyle, M.D.

Having a relatively easy and reliable way to gauge how far the disease has progressed could help doctors determine which patients are likely to benefit from drug treatment and to what extent. The new test can also provide insight into whether a person’s symptoms are likely due to Alzheimer’s versus some other cause and offer patients a less invasive option to diagnose the disease. It reduces reliance on PET scans and increases diagnosis accessibility, the FDA said in its announcement.

Burden of disease

About 7.2 million people age 65 and older in the U.S. are living with Alzheimer’s disease, according to new data from The Alzheimer’s Association. The World Health Organization estimates more than 57 million people worldwide live with dementia, with nearly 10 million new cases each year. This progressive disease places a huge burden on the U.S. health care system: the Alzheimer’s Association estimates that Alzheimer’s and other dementias will cost the U.S. about $384 billion in 2025 and as much as $1 trillion by 2050.

Family members often bear the burden of caregiving for loved ones with Alzheimer’s — most of which is unpaid. These caregivers provided more than 19 billion hours valued at $413.5 billion in care in 2024. Many are forced to curtail their own employment or drop out of the workforce completely, putting additional pressure on safety net programs like Medicaid.