A new blood test is offering doctors a faster way to identify signs of Alzheimer’s disease, but experts say it should not be treated as a routine screening test for everyone.
Alzheimer’s develops gradually, with changes in the brain often beginning years before noticeable memory problems appear. The disease is linked mainly to the buildup of beta-amyloid plaques and tau proteins, which are associated with damage to brain cells. Detecting these changes earlier could become increasingly important as new treatments aim to slow the progression of the disease.
The blood test, called the Lumipulse G pTau 217/β-Amyloid 1-42 Plasma Ratio, is made by Japanese diagnostics company Fujirebio. It measures two biomarkers associated with Alzheimer’s — pTau 217 and amyloid beta 1-42 — through a single blood sample.
The US Food and Drug Administration cleared the test in May 2025 as an aid to diagnosis for adults aged 50 and above who are showing signs of cognitive decline in specialised healthcare settings. The test has also started becoming available at some diagnostic laboratories in India, including through home sample collection.
However, the test is not designed to be used as a stand-alone diagnosis or as a preventive screening tool for people without symptoms.
In clinical trials involving patients already referred to specialist memory clinics, the test showed high agreement with established methods of detecting amyloid pathology. But experts have warned that its performance can vary in ordinary clinical settings. A Mayo Clinic study reported that the test detected most patients with amyloid pathology but also produced positive results in a significant number of people who did not have the condition.
This raises concerns about false-positive results, particularly among people who have no symptoms but take the test because of a family history of dementia.
The test could be more useful for people already experiencing memory or cognitive problems. Two anti-amyloid medicines, lecanemab and donanemab, have now been approved in India for certain patients with early Alzheimer’s disease. However, doctors need confirmation of amyloid pathology before starting these treatments.
In countries such as the US and parts of Europe, doctors can confirm amyloid pathology through an amyloid PET scan or cerebrospinal-fluid testing. Amyloid PET is not currently a routine clinical option in India, while cerebrospinal-fluid testing is still not widely available.
For people without symptoms, experts continue to recommend established preventive measures such as controlling blood pressure, staying physically active, treating hearing loss, getting adequate sleep and maintaining social and cognitive activity.
Doctors therefore advise that the new blood test should be used as part of a proper medical assessment, rather than as a simple test that anyone can take to find out whether they will develop Alzheimer’s.
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