For the first time, the U.S. Food and Drug Administration has cleared a blood-based test to aid in diagnosing Alzheimer’s disease (AD). The test, which detects the presence of brain amyloid plaques that are a hallmark of the disease, requires just a blood draw, making it as accessible as a cholesterol test during a regular office visit.
While AD blood tests have been available for years for use in research, the FDA’s approval means the test now can be used for determining if people with cognitive changes have markers of Alzheimer’s. Intended for people 55 and older who have memory problems or other signs of symptoms of AD, it could change the way doctors diagnose and treat the disease as new interventions become available. After all, there have been a flurry of new anti-amyloid therapies for Alzheimer’s disease. This test could help suggest who may potentially benefit from one of those new therapies.
It could also indicate the way forward for a blood test for Parkinson’s.
Blood-Based Testing for Parkinson’s
In 2023, researchers validated a biomarker tool that detects misfolded alpha-synuclein, a hallmark of PD in the same way amyloid plaques are hallmarks of AD. That tool, the alpha-synuclein seeding amplification assay (aSyn-SAA), is currently only validated in spinal fluid, but researchers are working diligently to develop the same test in skin and blood samples with the support of The Michael J. Fox Foundation (MJFF).
Currently, aSyn-SAA has received backing as a research tool with its applications in spinal fluid, though the Parkinson’s field is working on a blood-based version. The results of blood-based tests in Alzheimer’s have shown how it can be done and what data is needed to get FDA clearance.
“We have been working toward blood-based biomarkers for quite some time,” said MJFF chief scientist Mark Frasier, PhD. “The approval of a blood test in Alzheimer’s is an important milestone for neurodegenerative diseases broadly, and it provides a path to follow for Parkinson’s research.”
MJFF has provided support to a variety of projects advancing blood-based testing and continues to look for ways to expand this work. MJFF recently completed review of a new batch of aSyn-SAA-related projects through an open invitation to submit funding requests. Additional blood-based testing could be funded through MJFF’s Parkinson’s Progression Markers Initiative (PPMI) Biofluid Biomarkers Program. The program has also invited the scientific community to submit projects that would help identify and advance biomarkers of alpha-synuclein pathology beyond the spinal fluid test.
Role of Blood Testing in Treatment
Early and accurate diagnosis of neurodegenerative diseases like Alzheimer’s and Parkinson’s can play an important role in the development of new drug therapies to slow or stop the disease progression. There are indications that both diseases start to develop in the brain years before symptoms of the disease become apparent, and additional evidence shows there is often biological overlap between the two diseases.
The blood test for Alzheimer’s — and any future blood test for Parkinson’s — could play a pivotal role in selecting the right participants for clinical trials testing targeted therapies. Ideally, blood tests could also be used to monitor disease progression over the course of clinical trials to demonstrate whether therapies in testing are effective.
What’s the Bottom Line?
This FDA approval for a blood-based test for Alzheimer’s is a promising development in the field. It has immediate and broad implications for research and more efficient clinical trial testing as well as effects on diagnosis and care.
As always, if you’re considering this test for Alzheimer’s or a test for Parkinson’s, meet with a specialist who can talk you through the pros, cons and limitations of testing.
And remember, these (and future) breakthroughs are not possible without you and your participation in research. Learn more about PPMI and join the study that’s changing everything.