New Blood Test Tech Could Change How We Treat Alzheimer's Disease
Studies suggest that new blood tests could slash wait times for disease diagnosis and treatment availability.
Currently, diagnosing Alzheimer’s disease can take months or years, with doctors conducting memory and think tests, PET spans, and spinal taps to detect the buildup amyloid-beta protein, a telltale sign of the disease.
And a delay in diagnosis means a delay in treatment. Individuals exhibiting signs of early-stage Alzheimer’s must undergo tests to confirm the presence of a buildup of amyloid-beta before highly demanded new medications — like Eli Lilly’s donanemab, Kisunla, and Eisai and Biogen’s Leqembi — can be prescribed. However, experts told USA Today that these tests are often delayed or “inequitably deployed because there's a shortage of Alzheimer's specialists and many people can't access clinics that can perform PET scans or spinal taps to detect amyloid-beta.”
Now a new generation of blood test technology is vying to replace the arduous process, allowing for earlier access to FDA-approved drugs, and helping researchers more efficiently run studies evaluating experimental medications for the disease.
In a newly released JAMA study, researchers from Lund University in Sweden found that its p-tau217 blood tests could identify individuals likely to be in early stages of Alzheimer’s disease without having shown signs of memory and thinking problems. During the clinical trial, 1213 patients underwent evaluation of cognitive symptoms between February 2020 and January 2024. Biomarker cutoff values were established in an independent cohort and applied to a primary care cohort (n=307) and a secondary care cohort (n=300).
“… one plasma sample per patient was analyzed as part of a single batch for each cohort,” the study authors wrote. “The blood test was then evaluated prospectively in the primary care cohort (n = 208) and in the secondary care cohort (n = 398); one plasma sample per patient was sent for analysis within two weeks of collection.”
Blood tests were analyzed by mass spectrometry to determine the ratio of plasma phosphorylate tau 217 (p-tau217) to non-p-tau217 alone and when combined with amyloid-b 42 and amyloid-b 40 plasma ratio. The study concluded that the p-tau217 tests could predict 79% to 86% of cases in which cognitively normal people also had a buildup of amyloid-beta confirmed by PET scans or spinal taps, meaning that the tests could identify the signs of the disease before symptoms began.
“Blood tests are revolutionizing Alzheimer’s detection, diagnosis and ultimately treatment, and this recent JAMA study is further validation that C2N’s blood test is highly accurate and sensitive,” Howard Fillit, MD, co-founder and chief science officer of the Alzheimer's Drug Discovery, said in an emailed statement to MD+DI.
The study researchers said that more studies were needed to confirm the clinical trial’s findings but highlighted that it might show that the blood tests could reduce the need for specialists to use PET scans or spinal taps to diagnosis the disease.
“With more studies like this one, blood tests will soon replace more invasive and costly PET scans as the standard of care and serve as the first line of defense in diagnosing the disease,” Fillit said in his statement to MD+DI. “After many years of research, the field is in a place where we have novel biomarkers and diagnostics to support a diagnosis, like how cholesterol is used to help detect heart disease. The diagnostic framework for Alzheimer's—an incredibly complex disease—is constantly evolving.”
ALZpath, a testing company, is widely deploying its proprietary tau tests through commercial testing platforms already used in hospitals and other medical settings and has licensed its technology to companies like Roche and Beckman Coulter.
However, there is more than one player in the Alzheimer’s diagnostic blood test game.
In a Journal of the American Medical Association study of more than 1,200 patients with signs of the disease, researchers found that the Precivity AD2 blood test (APS2) detected the disease more often than physicians. The test, which measures ratios of tau and amyloid-beta, accurately detected around 90% of cases, even among patients with complicated medical histories including kidney disease.
“These results were especially impressive considering that older populations in primary care often have medical conditions that can influence or vary the concentrations of p-tau217,” Sebastian Plamqvist, MD, PhD, lead study author, told the Alzheimer's Association.
Among 698 patients seen at memory clinics, APS2 was around 90% accurate at identifying Alzheimer's while specialists were only 73% accurate. Additionally, among 515 patients seen in primary care, APS2 was also around 90% accurate while primary care physicians were 63% accurate, according to the Alzheimer's Association.
As a whole, blood test diagnostics for Alzheimer’s could reduce wait times for eligibility of new treatments. Research reported at AAIC 2024, the Alzheimer's Associations annual meeting, suggested that using “high-performing blood tests in primary care could identify potential Alzheimer’s patients much earlier so specialists can determine if they are eligible for new treatments.”
Using a well-established forecasting model to predict wait time for individuals eligible for treatment, it suggested that by 2033, people will wait an average of nearly six years to understand if they could be eligible for new treatments if their primary care doctor only used brief cognitive assessments to make referrals. If blood tests were used to rule out Alzheimer's, the average wait time would be reduced to 13 months as fewer patients would need to see a specialist.
“Our results suggest using blood tests to identify potential candidates for treatments could make a significant difference in treating people with early Alzheimer’s,” said Soeren Mattke, MD, DSc, lead author of forecasting model and director of the Brain Health Observatory, at the University of Southern California, Los Angeles, to the Alzheimer’s Association. “Currently, eligible patients are falling outside of the treatment window because it takes so long to receive a diagnosis. An easy-to-use blood test could help address that problem.”
About the Author
You May Also Like