The FDA’s recent approval of the first blood test to detect amyloid pathology—a hallmark of Alzheimer’s disease—is a breakthrough worth celebrating. For millions of patients and families, the test offers the promise of earlier diagnosis and, with it, improved access to newly available disease-modifying treatments. Used in combination with other clinical assessments, the blood test holds enormous potential to help accelerate Alzheimer’s research by enabling faster, more scalable identification of eligible participants for trials.
To put this breakthrough into perspective, it is important to remember where Alzheimer’s research was just 10-15 years ago. We knew that extracellular amyloid plaques and intracellular tau tangles were the key biomarkers of the disease, but we were unable to see Alzheimer’s pathology in the living brain at scale. An official differential diagnosis could only be made after a patient died.
Amyloid PET scans changed everything. The first beta-amyloid imaging agent approved by the FDA in 2012 allowed researchers and clinicians to see amyloid plaques in patients with minimal time and risk. While still viewed as a gold standard, the operational complexity of manufacturing and delivering the required tracer and then conducting a PET scan can be problematic. The tests are expensive, patients must often travel long distances to find a center and the diagnostic agent dose must be custom made for each appointment.
Fast forward to today, there are multiple blood-based biomarkers for detecting Alzheimer’s disease in various stages of use or clinical development—and now, an FDA-approved option available for commercial use that is more likely to be covered by insurers, potentially broadening access. Just a decade ago, a scientifically reliable blood test for Alzheimer’s was still a distant vision. Today’s blood tests have the potential to serve as an alternative to PET scans, helping expand patient access to diagnostic tools and clinical care. As is common in medicine, the first disease-modifying therapies in Alzheimer’s are not for everyone, underscoring the need for continued research to develop multiple treatment options.
The newly approved blood test could dramatically increase the speed and operational efficiency of Alzheimer’s clinical trials. Rates of clinical trial enrollment and completion are much slower for Alzheimer’s disease than other therapeutic areas, and often the recruiting period is double the length of the trial treatment period itself. Faster completion of clinical trials increases our understanding of Alzheimer’s and our ability to find treatments and a cure.
The Clinical Trial Recruitment Lab (CTRL) at the USC Schaeffer Center for Health Policy & Economics is building an evidence base on effective Alzheimer’s recruitment strategies to help accelerate progress across the field. For example, the AlzMatch Study—led by the Alzheimer’s Therapeutic Research Institute (ATRI) at the Keck School of Medicine of USC—has shown promising results using plasma biomarkers to identify eligible candidates for preclinical Alzheimer’s trials. The AlzMatch program is now being scaled for broader implementation, with an expanded version already underway that engages a larger pool of participants and clinical trial sites to further validate this innovative approach to Alzheimer’s research.
In the AHEAD Study, researchers successfully incorporated blood testing procedures alongside PET scans, enabling them to exceed an enrollment target of 1,400 participants on deadline. Ultimately, 1,600 of the more than 20,000 who had been screened were enrolled in this randomized trial. Researchers only had to complete 4,400 PET scans, and the number would have been about half that if accurate blood test screening had been used for the entire study. The tests used in these studies were only available for research. The commercially available blood test has the potential to further accelerate progress.
And we know speed is essential. Detection and diagnosis of Alzheimer’s and other dementias often occur late, if at all. As a result, patients often lose the opportunity to participate in clinical trials because their disease is too advanced.
Research is exploring not only patients’ willingness, but also their ability to participate in Alzheimer’s trials—highlighting the need to reduce structural and systemic barriers to engagement. Doing so will ensure that more patients can benefit from advances that not too long ago seemed far out of reach.
