The US Food and Drug Administration on Monday cleared the first blood-based diagnostic test for Alzheimer's disease intended for use in primary care settings. Family physicians can now identify the disease years before severe symptoms emerge using a plasma assay that measures phosphorylated tau and amyloid ratios associated with the condition.

Until now, confirming Alzheimer's required costly positron emission tomography scans or invasive lumbar punctures, procedures available mainly at specialist memory clinics. The FDA designed the new test for patients aged 55 and older who present with cognitive complaints, broadening diagnosis beyond academic medical centres.

The clearance follows research warning of a surging dementia burden. A Lancet analysis published last week projected that global dementia cases would triple by 2050, intensifying pressure on health systems to diagnose patients earlier and connect them to new anti-amyloid therapies such as lecanemab and donanemab.

The Alzheimer's Association welcomed the decision, saying accessible blood testing could reduce diagnostic delays that leave many patients untreated until the disease is advanced. Neurologists cautioned that a positive blood result still requires confirmatory evaluation before patients begin treatment with infusion drugs that carry risks of brain swelling.

Analysts at Leerink Partners predicted the approval could accelerate uptake of newly approved Alzheimer's drugs, which depend on early detection to deliver measurable benefit. The manufacturer said it expected the test to reach laboratories across the United States within weeks.