Jan. 23, 2024 – A blood test that’s already commercially available is nearly as accurate as more invasive tests like spinal taps at detecting potential signs of Alzheimer’s disease, a new study shows.
The test looks for a protein in the blood called p-tau217, and the independent researchers found that large changes in that biomarker were also suggestive of changes in known biomarkers of Alzheimer’s disease called amyloid beta and tau. The blood test was up to 97% accurate, and the researchers found that about 20% of people in the study would need follow-up testing to confirm whether they had conclusive signs of Alzheimer’s.
Currently, the most accurate tests for diagnosing Alzheimer’s disease and detecting amyloid beta and tau involve collecting cerebrospinal fluid or having highly sensitive imaging like PET scans. Those tests can be difficult for many people to have because of high cost or lack of access, such as living far away from where the tests are available. The blood test used in the study is made by the California-based firm ALZpath Inc., and CNN reported that the test could cost between $200 and $500.
The study was published Monday in the journal JAMA Neurology. It was led by researchers from the University of Gothenburg in Sweden and from King’s College London, who analyzed data for 786 people.
They wrote that blood tests for p-tau217 could play an “important role … as an initial screening tool in the management of cognitive impairment,” noting that the test could help identify people who may benefit from existing treatments that target amyloids in the brain.
Alzheimer’s disease is the most common form of dementia, which affects 6.7 million people ages 65 and older in the U.S. That number is projected to reach 14 million by 2060, according to the CDC. It’s common for older adults to have subtle changes in memory, thinking, and reasoning skills, but severe changes that interfere with everyday life can be a sign of dementia.
The authors explained that the “use of a blood biomarker is intended to enhance an early and precise [Alzheimer’s disease] diagnosis, leading to improved patient management and, ultimately, timely access to disease-modifying therapies.” But they cautioned that further study is needed to apply their results to the general population, particularly because one-third of the people in the study were already diagnosed as cognitively impaired.
