1. A Huge Step Forward
In mid‑May 2025, the U.S. Food and Drug Administration approved the first-ever blood test to help diagnose Alzheimer’s disease. It’s called Lumipulse G pTau217/β‑Amyloid 1‑42 Plasma Ratio, made by Fujirebio Diagnostics. sciencex.com+12U.S. Food and Drug Administration+12alzra.org+12
2. How It Works
The test measures two proteins in your blood:
- pTau217
- β‑amyloid 1‑42
By calculating their ratio, doctors can see if you have signs of amyloid plaques—clumps in the brain linked to Alzheimer’s. Traditionally, detecting these plaques involved spinal taps or PET brain scans—now replaced by a simple blood draw. Forbes+12U.S. Food and Drug Administration+12Reuters+12Medical News Today
3. Who It’s For
The test is approved for people 55 and older who already have symptoms like memory loss or confusion. It’s not meant for healthy individuals with no symptoms. San Francisco Chronicle+6AP News+6Verywell Health+6
4. Accuracy You Can Count On
In clinical trials involving 499 patients:
- ~92% of positive results matched later scanning or spinal tap results.
- ~97% of negative results were confirmed by traditional tests.
About 20% of cases fell into a “gray zone” needing more testing. healthcare.utah.edu+9Verywell Health+9Champions for Health+9
5. Why It Matters Now
New treatments like Leqembi and Kisunla only work well when started early—before severe cognitive decline. This blood test can speed up diagnosis and treatment. statnews.com+11AP News+11Verywell Health+11 Doctors say this could open access for people who don’t live near memory clinics or neurologists. Verywell HealthAlzheimer’s Association
### 6. Important Limitations
- The test isn’t a definitive diagnosis—it should be used with memory exams and medical history.
- False positives (suggesting Alzheimer’s when it’s not) or false negatives (missing it) are possible.
- If the result is positive, more testing like PET scans or spinal taps may still be needed. alzra.org+2Alzheimer’s Association+2San Francisco Chronicle
7. What’s Next
The Alzheimer’s Association is rolling out clinical guidance to help doctors use blood-based biomarkers wisely—especially to decide when to test and how to interpret results. More tests from companies like Roche, Eli Lilly, and C2N Diagnostics are also nearing FDA review. AP News+1
✅ Bottom Line
Instead of invasive tests, you may soon be able to get screened for Alzheimer’s with just a blood draw—if you’re over 55 and already showing cognitive symptoms. While it’s not a standalone diagnosis, it offers a faster, more accessible path to early detection and treatment.
Concerned about someone who may be at risk for Alzheimer’s?
