New Delhi: The US Food and Drug Administration (FDA) has cleared a blood test developed by Switzerland-based pharma company Roche and US-based Eli Lilly that can help doctors check whether people with memory or thinking problems are likely to have changes in the brain linked to Alzheimer’s disease.
Called Elecsys pTau217, the test is the first and only FDA-cleared blood test that uses a single marker in the blood to both rule in and rule out Alzheimer’s-related changes, Roche said Monday. In simple terms, it can help doctors assess whether these changes are likely or unlikely to be present.
The test is meant for people aged 55 and above who have signs, symptoms or complaints of cognitive decline.
“FDA clearance of Elecsys pTau217 marks an important milestone in Alzheimer’s disease diagnosis,” Dan Malarek, president and CEO of Roche Diagnostics North America, said. He said the test could help bring Alzheimer’s testing closer to patients and help doctors decide what further tests or treatment may be needed.
Dementia is a condition in which a person’s memory, thinking or ability to manage everyday activities gradually declines. Alzheimer’s disease is the most common cause of dementia, accounting for an estimated 60-70 per cent of cases. About 57 million people were living with dementia worldwide in 2021, with nearly 10 million new cases every year, according to the World Health Organization.
The test looks for phosphorylated tau 217, or pTau217, a form of the tau protein that can indicate changes linked to Alzheimer’s in the brain.
It gives a positive, negative or intermediate result. A positive result means Alzheimer’s-related changes are more likely, while a negative result means they are less likely. An intermediate result may mean that further testing is needed.
The test does not diagnose Alzheimer’s on its own. Doctors will need to consider the result along with a person’s symptoms, medical history and other clinical information.
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Why the test matters
Doctors currently use Positron Emission Tomography (PET) brain scans or a test of cerebrospinal fluid, the fluid around the brain and spinal cord, to check for Alzheimer’s-related changes. These tests can be expensive, invasive and difficult to access in places without specialist centres.
The new blood test is simpler and less invasive. It could help doctors decide which patients need further tests or should see a specialist.
Roche said the test showed strong agreement with PET scans, which are currently used to detect amyloid, a protein that builds up in the brains of people with Alzheimer’s.
The test can also be run on more than 4,500 Roche laboratory machines already being used in the US, meaning laboratories may not need new equipment to offer it.
Such blood tests have been developed before, but the new Roche-Lilly test differs from them in two distinct ways.
First, it differs from Roche’s own earlier pTau181 test, cleared by the FDA in 2025. That test also measured a single protein in the blood, but was designed mainly to help rule out Alzheimer’s-related changes. The new pTau217 test uses just one marker as well, but can do both. It can help doctors assess whether these changes are likely to be present and whether they can be ruled out.
Second, it differs from other blood tests on the market that rely on more than one protein or marker to assess Alzheimer’s-related changes. Roche says that the pTau217 test can be applied consistently whether a patient is first seen in a primary care clinic or by a specialist. This is something multi-marker tests are not designed to do in the same way.
Jared R. Brosch, a neurologist at Indiana University Health, said in a statement that existing tests such as PET scans and tests of spinal fluid can detect Alzheimer’s-related changes but can be expensive, invasive and difficult for many patients to access.
What this means for early diagnosis
Alzheimer’s-related changes can begin in the brain years before symptoms such as memory loss appear. pTau217 is one of the blood markers being studied to detect these changes earlier.
But a positive test does not mean a person has dementia. Alzheimer’s-related changes can be present before symptoms, and memory problems can also have other causes.
According to Dr Manjari Tripathi, professor of neurology at AIIMS New Delhi, several such blood tests are already available in India. “There are many blood tests available. They are being used in India. These tests are surrogate biomarkers for early Alzheimer’s dementia or mild cognitive impairment of the Alzheimer’s kind,” she told ThePrint.
Surrogate biomarkers are measurable signs in the body that can indicate a disease or the changes linked to it, without directly diagnosing the disease itself. Dr Neha Pandita, senior consultant in neurology at Fortis Hospital, Noida, had earlier told ThePrint that blood tests could help detect Alzheimer’s-related changes earlier, but their results need to be interpreted by doctors along with the patient’s symptoms and other findings.
The new Roche test is not meant to screen healthy people, or predict who will develop dementia or track how well Alzheimer’s medicines are working; it is meant to help doctors assess people who already have cognitive symptoms and decide whether they need further tests.
(Edited by Nardeep Singh Dahiya)
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