September 25, 2024
One day soon, getting tested for Alzheimer’s may be as simple as going to your doctor’s office and getting a blood test, similar to the way we currently get tested for cholesterol.
Researchers report that a blood test detected 90 percent of early cases of Alzheimer’s disease. The results were far more accurate than those achieved by most doctors using standard tests of memory and thinking skills and CT brain scans, which can rule out other causes of memory loss like strokes or brain tumors.
A simple and affordable blood test would greatly facilitate the diagnosis of Alzheimer’s by identifying people with memory loss who are likely suffering from the disease. Blood tests could also help to identify patients who could benefit most from newer Alzheimer’s drugs like Kisunla and Leqembi, which are more effective at earlier stages of disease.
Experts increasingly believe that Alzheimer’s treatment needs to begin as early as possible, ideally before memory loss and other symptoms arise. By the time people become forgetful, their brains may be damaged to a point where most therapies are unable to fully heal them. Detecting Alzheimer’s at the earliest stages offers the best hope for delivering effective treatments.
In most primary care physician’s offices, it is difficult to diagnose Alzheimer’s disease and distinguish it from other disorders that may be causing memory loss and other symptoms. It often requires multiple doctor visits over several years to fully evaluate a patient and diagnose the disease.
Specialists can also perform PET scans and invasive spinal taps to look for markers of Alzheimer’s disease in the brain and cerebrospinal fluid. Short of a brain autopsy after death, such tests remain the gold standard for diagnosing Alzheimer’s but are cumbersome and expensive.
For the current study, researchers in Sweden performed the blood test on 1,213 men and women who were experiencing mild memory problems. Some were examined in primary care doctor’s offices, while others were evaluated in specialist memory clinics. The blood test used in the study measured levels of a form of the brain protein tau, which forms tangles in the brains of people with Alzheimer’s disease.
The doctors had access to patients’ cognitive tests of thinking and memory skills as well as CT scans, but not to the more definitive PET scan and spinal fluid tests.
The blood test determined “with 90 percent accuracy whether a person experiencing memory loss is suffering from Alzheimer’s,” said study author Sebastian Palmqvist, a professor of neurology at Lund University in Sweden. “Primary care doctors’ accuracy in identifying Alzheimer’s disease was 61 percent, while specialist physicians were correct 73 percent of the time.”
The findings underscore “the lack of good, cost-effective diagnostic tools, particularly in primary care, and indicate the potential improvement in diagnosis with the adoption of this blood test in health care settings,” Dr. Palmqvist said. The results were published in the medical journal JAMA.
Blood tests for Alzheimer’s are under evaluation at medical centers across the country. More study is needed to determine who might benefit from a blood test, and what follow up tests may be needed to confirm a diagnosis. But as medical technologies improve, these findings add to growing evidence that a blood test for Alzheimer’s could soon be coming to a clinic near you.
By ALZinfo.org, The Alzheimer’s Information Site. Reviewed by Eric Schmidt, Ph.D. Fisher Center for Alzheimer’s Research Foundation at The Rockefeller University.
Source: Palmqvist S, Tideman P, Mattsson-Carlgren N, et al: “Blood Biomarkers to Detect Alzheimer Disease in Primary Care and Secondary Care.” JAMA, July 28, 2024
