The US Food and Drug Administration (FDA) has approved a second blood test to detect Alzheimer’s disease, potentially speeding diagnosis for millions of patients.
The Elecsys pTau181 test measures protein levels in blood plasma that act as biomarkers for the degenerative brain disorder, offering a simpler alternative to costly brain scans for people aged 55 and over with symptoms of cognitive decline.
The approval marks another step toward making Alzheimer’s detection more accessible through routine blood testing rather than specialist imaging that can take weeks or months for diagnosis.
Developed by Swiss biotech company Roche with Eli Lilly, the test builds on evidence that certain blood proteins can indicate brain changes linked to Alzheimer’s disease.
The pTau181 protein it measures is a biomarker — a biological indicator of disease activity.
“By bringing Alzheimer’s blood-based biomarker testing into primary care, we can help patients and their clinicians get answers sooner to support them earlier in their journeys,” said Brad Moore, CEO and president of Roche Diagnostics North America.
The FDA approved the first Alzheimer’s blood test, Lumipulse, earlier this year.
That test, made by Japanese company Fujirebio, detects different protein biomarkers linked to the disease.
Alzheimer’s is currently diagnosed using brain scans that detect toxic protein build-up and other hallmarks of the disease. These procedures are expensive, often involve long waiting times, and are not widely available.
Blood tests could make early screening easier in primary care, though experts stress they cannot provide a definitive diagnosis on their own.
“This is another important step toward expanding access to Alzheimer’s disease diagnostic tools,” said Dr Joanne Pike, president and CEO of the Alzheimer’s Association.
“At the same time, it is important to understand this test is designed to rule out the presence of amyloid plaques. It is not a test that will give an Alzheimer’s disease diagnosis, nor is it a standalone tool for detection.”
Amyloid plaques are abnormal protein deposits that form between brain cells and are a hallmark of Alzheimer’s.
The blood test helps determine whether these plaques are likely present, guiding doctors on whether further testing is needed.
Roche said a clinical study involving more than 300 participants showed the test correctly identified people without Alzheimer’s signs in nearly 98 per cent of cases.
his accuracy could help reduce unnecessary brain scans and related costs.
Researchers at UC San Diego recently reported that rises in blood proteins following brain inflammation and nerve cell damage were linked to cognitive decline — evidence supporting development of blood-based early detection tools.
Dr Richard Isaacson, who established one of the first Alzheimer’s prevention clinics in the US, told CNN that additional blood tests would likely be needed to give a full picture of brain health.
“This single Roche test is looking at pTau181 as a single protein marker,” he said.
“But for people who are at risk for Alzheimer’s, to truly have the best accuracy and the most granularity to understand what’s going on, we’re going to need a panel of tests.
“And then we’re going to need to follow these tests over time.”
The Alzheimer’s Association said the test could help avoid unnecessary and expensive diagnostic procedures.
The Elecsys pTau181 test is designed to be used alongside clinical evaluation and other diagnostic tools, not as a replacement for full medical assessment.
Patients with positive results would typically undergo additional testing to confirm a diagnosis.
Both approved blood tests represent progress in improving Alzheimer’s detection, though experts emphasise that diagnosis still requires a combination of clinical, imaging and laboratory assessments.
As blood-based biomarker research advances, scientists hope combining several markers will give a clearer picture of brain health and disease progression — potentially allowing earlier intervention and better patient outcomes.
