New Blood Tests Show Promise for Diagnosing Alzheimer's Faster and More Accurately
WASHINGTON (AP) — New blood tests could revolutionize the speed and accuracy of Alzheimer's disease diagnoses, researchers reported Sunday. However, the effectiveness of these tests varies significantly, with some proving much more reliable than others.
Diagnosing Alzheimer's typically requires confirming the presence of beta-amyloid, a sticky protein, through invasive brain scans or spinal taps. Many diagnoses are based on symptoms and cognitive evaluations alone. However, several new blood tests have emerged, aiming to detect Alzheimer’s signs more conveniently and cost-effectively. Despite their potential, these tests are not yet widely used due to limited data on their accuracy, lack of FDA approval, and minimal insurance coverage.
Dr. Suzanne Schindler, a neurologist at Washington University in St. Louis, highlighted the disparity in test reliability. "Some are highly accurate, while others are almost as random as a coin flip,” she said.
Rising Demand for Early Alzheimer’s Diagnosis
With over 6 million Americans and millions more globally affected by Alzheimer’s, early and accurate diagnosis is crucial. The disease is marked by amyloid plaques and abnormal tau proteins, leading to severe cognitive decline. New treatments like Leqembi and Kisunla can modestly slow symptom progression by targeting amyloid, but they are only effective in the disease’s early stages. Diagnostic methods like spinal fluid analysis and PET scans are either invasive, costly, or difficult to access.
Dr. Schindler noted the challenge even specialists face in diagnosing Alzheimer’s. "I often suspect Alzheimer’s but get negative results from current tests."
Blood Tests Show Real-World Potential
A new study involving around 1,200 patients in Sweden reveals that blood tests can be effective in real-world settings, especially in primary care. The study compared blood tests with traditional diagnostic methods and found blood tests to be significantly more accurate. In this study, blood tests had a 91% accuracy rate compared to 61% for primary care doctors’ initial diagnoses and 73% for specialists.
Which Blood Tests Are Most Reliable?
The variety of blood tests available can be overwhelming, measuring different biomarkers in various ways. Dr. John Hsiao of the National Institute on Aging suggests that tests demonstrating over 90% accuracy should be prioritized. The most promising tests currently measure p-tau217, a tau protein variant correlated with plaque buildup. High levels of p-tau217 strongly suggest Alzheimer’s, while low levels are indicative of other causes of memory loss.
Several companies, including ALZpath Inc., Roche, Eli Lilly, and C2N Diagnostics, are developing p-tau217 tests.
Guidelines for Blood Test Use
Currently, only doctors can order these blood tests. The Alzheimer’s Association is working on guidelines, and companies are seeking FDA approval to establish clearer usage protocols. For now, these tests should be used by physicians for individuals with memory issues, as they help differentiate between patients who might need further evaluation and those who can be reassured.
Dr. Sebastian Palmqvist, who led the Swedish study, emphasized the tests' potential to aid primary care physicians. However, they are not recommended for asymptomatic individuals concerned about genetic risks unless part of a research study. Alzheimer's symptoms can begin up to two decades before diagnosis, and preventive measures remain limited to lifestyle changes while research continues into potential therapies for high-risk individuals.
