Alzheimer’s: New Blood Tests Offer Earlier Diagnosis & Treatment Hope

For decades, diagnosing Alzheimer’s disease (AD) has required access to specialist memory clinics, neuroimaging, or invasive cerebrospinal fluid (CSF) testing. That paradigm is beginning to shift. In 2025, the US Food and Drug Administration (FDA) cleared the first blood-based biomarker tests intended to aid in the assessment of AD.

A New Era in Alzheimer’s Diagnosis

“Blood-based biomarkers for Alzheimer’s disease are probably the most important breakthrough in 20 years,” says Craig Ritchie, honorary professor of the psychiatry of ageing at the University of Edinburgh. The FDA cleared Roche’s Elecsys pTau181 assay in October 2025, following the approval of Fujirebio’s Lumipulse G pTau217/β-amyloid 1-42 plasma ratio test in May of the same year.

How the Tests Work

Both assays detect proteins associated with AD pathology in plasma, offering a less invasive alternative to traditional methods like positron emission tomography (PET) imaging or lumbar puncture. The arrival of disease-modifying therapies, such as lecanemab and donanemab, which target amyloid, has increased the urgency for accurate and earlier diagnoses. These treatments are most effective when administered before substantial neuronal loss occurs and require confirmation of AD pathology.

Different Tests, Different Purposes

While both tests have been cleared by the FDA, they serve distinct clinical purposes. Roche’s Elecsys measures tau protein phosphorylated at amino acid 181 (pTau181). Fujirebio’s Lumipulse assay measures both pTau217 and a β-amyloid peptide of amino acids 1–42, calculating their ratio to correlate with the presence of amyloid plaques. The Lumipulse assay is intended for use in specialized care settings.

Alicia Algeciras-Schimnich, a consultant at the Mayo Clinic in Rochester, Minnesota, emphasizes that the Roche test is best considered a rule-out or screening test, with a positive predictive value of around 22%. The Fujirebio assay, she says, functions more as a confirmatory test, though indeterminate results still require follow-up.

What’s Next for Blood-Based Biomarkers?

Whether FDA clearance will translate into widespread clinical use remains uncertain. Joshua Grill, director of the Institute for Memory Impairments and Neurological Disorders at the University of California, Irvine, calls the approvals a “milestone,” but cautions against assuming immediate impact. Physician comfort with the tests and professional guidelines will be key factors in their adoption.

Research is ongoing to determine how blood biomarkers improve care outside specialist settings. The BioFINDER-Primary Care study is evaluating whether adding plasma biomarkers alongside cognitive assessments improves diagnostic accuracy and referral decisions. There is also debate about whether these tests should be used in asymptomatic people, with some experts recommending against it until symptom-delaying treatments are available.

These tests are already reshaping clinical trials of AD, making it easier to identify patients who truly have the disease. They also expand access to biomarker testing, particularly for those in underserved regions. However, recent data suggests the need for continued validation of test performance in real-world situations.

Frequently Asked Questions

What is the difference between the Roche and Fujirebio tests?

Roche’s Elecsys measures pTau181 and is best used as a rule-out or screening test. Fujirebio’s Lumipulse measures both pTau217 and a β-amyloid peptide and functions more as a confirmatory test.

Are these tests definitive for an Alzheimer’s diagnosis?

No, these tests should not be used as standalone measures. They must be interpreted within the context of their intended application and alongside other clinical information, according to Alicia Algeciras-Schimnich.

When might these tests be used in primary care?

These tests could be used as early triage tools, helping clinicians rule out AD before pursuing more invasive or costly investigations, according to Craig Ritchie.

As these new diagnostic tools become more widely available, will they fundamentally change how we approach Alzheimer’s disease and the care of those at risk?