SouthernWorldwide.com – A new generation of blood tests designed to predict the risk of Alzheimer’s disease shows promise for earlier detection, but experts are urging caution regarding the accuracy and reliability of their results.
A recent study, supported by the National Institutes of Health, examined a blood test that measures levels of p-tau217. This protein is known to accumulate in the brain as Alzheimer’s disease progresses.
The study involved over 600 older adults who did not exhibit any symptoms of Alzheimer’s. Researchers found that repeated blood tests could predict the onset of symptoms with a median absolute error of approximately three to four years. Higher levels of p-tau217 were consistently linked to an earlier appearance of symptoms.
According to the study’s findings, an individual with elevated p-tau217 levels at age 60 might typically develop symptoms around 20 years later. Conversely, if p-tau217 levels become elevated at age 80, symptoms tend to manifest much sooner, after about 11 years.
The researchers emphasized that these findings, published in Nature Medicine, require further validation in broader and more diverse populations. They noted that the predictive accuracy of the test may not yet be sufficient for widespread individual clinical use.
“In the near term, these models will accelerate our research and clinical trials,” stated Dr. Suzanne Schindler, the lead investigator from Washington University in St. Louis, in an NIH press release. “Eventually, the goal is to be able to estimate when individuals are likely to develop symptoms, which will help them and their doctors to develop a plan to prevent or slow symptoms.”
With an increasing number of Alzheimer’s treatments becoming available, there is a growing need for biomarker confirmation of the disease, according to Dr. Sheena Aurora, Vice President of Medical Affairs for the Alzheimer’s Association in Chicago.
“Blood-based biomarker tests can improve the accuracy and speed of diagnosis when used as a complement to other testing, offering a path to earlier Alzheimer’s detection,” Dr. Aurora told Fox News Digital. She added that these tests are relatively inexpensive and more accessible compared to PET scans or MRIs.
“For many, early detection can bring peace of mind, time to plan ahead, agency over decisions and the opportunity to try treatments that slow disease progression,” she explained.
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Two Alzheimer’s blood tests have already received clearance from the FDA. These include the Fujirebio Lumipulse G pTau217/β-Amyloid 1-42 Plasma Ratio, cleared for symptomatic adults aged 55 and older, and the Roche Elecsys pTau181 Plasma, cleared for initial assessment in primary care for adults aged 55 and over experiencing symptoms of cognitive decline.
Dr. Aurora cautioned that while several other lab-developed tests are emerging, not all are identical, and they do have limitations. The Alzheimer’s Association’s clinical guidelines currently recommend using blood tests primarily in specialized care settings for patients with cognitive impairment, as this is the only context where strong evidence supports their effective use.
“We do not recommend the use of blood biomarker tests in people who are not experiencing symptoms,” Dr. Aurora stated. “There currently is not substantive data about use of these tests in primary care settings or for people who are not cognitively impaired.”
Diagnosing Alzheimer’s is typically a multi-step process involving various types of tests, and blood testing can serve as an important component of this diagnostic journey. However, Dr. Aurora emphasized that current Alzheimer’s blood biomarker tests are not standalone diagnostic tools; such a test does not yet exist.
Blood tests are not a substitute for a comprehensive clinical evaluation and should always be ordered and interpreted by a healthcare professional within the context of clinical care. The Alzheimer’s Association’s guidelines also highlight that accuracy can vary significantly among different tests, and many available blood biomarker options do not meet recommended performance standards.
Experts also warn about the potential for false positives, which can lead to significant anxiety for individuals. Research indicates that people with chronic kidney disease, for instance, may show higher levels of Alzheimer’s blood biomarkers even in the absence of the disease, underscoring the critical need for healthcare providers to carefully analyze test results.
As new research continues to demonstrate the potential of blood tests, Dr. Aurora stressed the importance of enhanced education for both patients and healthcare providers. Clear clinical follow-up protocols after receiving results are also crucial to fully realize their potential across different care settings.
“Studies in these areas are being conducted, and we expect to learn more at the 2026 Alzheimer’s Association International Conference (AAIC 2026), July 12–15 in London and online,” she added.
Dr. Aurora also mentioned the Alzheimer’s Screening and Prevention (ASAP) Act, which aims to broaden access to new blood tests by establishing a pathway for Medicare to cover FDA-approved or cleared blood biomarker screening tests. Under current law, Medicare can only cover preventive services if authorized by Congress or recommended by federal guidelines, a restriction that has delayed coverage for emerging Alzheimer’s tests.
