- Two FDA-cleared blood tests from Fujirebio and Roche can now detect tau protein tangles and beta-amyloid plaques — hallmarks of Alzheimer’s — but are designed only for patients already showing signs of cognitive decline.
- A 2025 Alzheimer’s Association survey found 91% of Americans would want a simple blood test to detect the disease, yet 15% of healthy 50-year-olds already have abnormal amyloid levels without developing Alzheimer’s — rising to 50% by age 85.
- Without approved treatments for asymptomatic people, neurologists say broad testing of healthy individuals creates more anxiety than actionable insight; drugmakers Eli Lilly, Biogen, and Roche are racing to change that with prevention trials.
- Results can fluctuate based on daily factors like illness or even whether a patient has eaten — requiring follow-up imaging and testing before any clinical conclusion can be drawn.
What Happened?
For years, Alzheimer’s diagnosis meant invasive spinal taps, expensive brain imaging, or written memory tests. Two new FDA-cleared blood tests are beginning to change that: one from Fujirebio Diagnostics and one from Roche, both measuring tau protein variants linked to Alzheimer’s, with Fujirebio’s also measuring beta-amyloid. The tests are designed to evaluate patients with early symptoms of cognitive decline — not to screen the general population. But demand from healthy, symptom-free people is already outpacing that intent, with neurologists reporting a wave of patients requesting the tests, often citing family histories of dementia or Alzheimer’s disease.
Why It Matters?
The tests sit at the intersection of consumer demand for health data and the limits of what medicine can currently do with it. While 91% of Americans say they’d want an Alzheimer’s blood test, the clinical reality is complicated: a large share of healthy older adults already have amyloid buildup without ever developing the disease. Positive results without actionable treatment create distress without benefit. The commercial and scientific picture is evolving rapidly, however — Eli Lilly, Biogen/Eisai, and Roche are all running prevention trials using blood tests to identify eligible participants, and the same tests could eventually form the backbone of routine Alzheimer’s screening once preventive drugs exist. Researchers are also exploring whether finger-prick home tests could expand access further, with early data showing promise.
What’s Next?
The next milestone is a preventive treatment. If any of the amyloid-targeting drugs currently in trials prove effective in asymptomatic patients, the FDA-cleared blood tests would instantly become a standard screening tool — shifting the market dramatically. Until then, neurologists are steering healthy patients toward brain MRI baselines and cognitive benchmarks rather than blood biomarker tests. The medical community is broadly aligned: more data is coming, and those who want early information can pursue it, but the current standard of care doesn’t yet support routine screening of the healthy population.
Source: The Wall Street Journal
