FDA Approves Blood Test to Rule Out Alzheimer’s Disease

The US Food and Drug Administration (FDA) has granted approval for a blood test aimed at assisting in the assessment of Alzheimer’s disease and other cognitive decline causes. This advancement allows for a clearer understanding of when Alzheimer’s can be ruled out in patients exhibiting symptoms. The test, known as the Elecsys pTau181, was developed by Roche Diagnostics in collaboration with Eli Lilly, and is intended for use by primary care physicians for adults aged 55 and older in the United States.

In a statement released on Monday, Brad Moore, President and CEO of Roche Diagnostics North America, expressed optimism about the test’s potential impact. He noted, “By bringing Alzheimer’s blood-based biomarker testing into primary care, we can help patients and their clinicians get answers sooner to support them earlier in their journeys.” With estimates suggesting that over 42% of individuals aged 55 and above will develop dementia, and approximately 92% of adults with mild cognitive impairment remaining undiagnosed, this test could play a pivotal role in early assessment.

Understanding the Test’s Functionality

The Elecsys pTau181 test identifies patients unlikely to have Alzheimer’s disease. A negative result indicates that further evaluation is necessary, while a positive result prompts recommendations for additional testing. Dr. Joanne Pike, President and CEO of the Alzheimer’s Association, emphasized the importance of this tool, stating, “This is another important step toward expanding access to Alzheimer’s disease diagnostic tools.”

She cautioned that while the test helps rule out the presence of amyloid plaques, it does not provide a definitive Alzheimer’s diagnosis. “By using a ‘rule out’ initial tool in the primary care setting, we can help people who are not living with Alzheimer’s get to the root of their cognitive symptoms faster,” she added.

The Elecsys pTau181 test is the second blood-based biomarker test to receive FDA clearance for Alzheimer’s disease in 2023, following the Lumipulse G pTau217/ß-Amyloid 1-42 Plasma Ratio developed by Fujirebio, which received approval in May. The new Roche test measures the protein pTau181 in blood plasma, with elevated levels indicating a higher likelihood of Alzheimer’s disease and other neurodegenerative conditions.

Clinical Implications and Future Considerations

According to a clinical study involving 312 participants, the Elecsys pTau181 test achieved a negative predictive value of 97.9%, meaning that negative results strongly suggest the absence of Alzheimer’s-related pathology. Dr. Laura Parnas, Director of Medical and Scientific Affairs at Roche Diagnostics, noted, “When the test result is negative, there’s a very high likelihood the person does not have Alzheimer’s-related pathology.”

Despite this promising outcome, experts like Dr. Richard Isaacson, a preventive neurologist, urge caution regarding the test’s mass adoption. He stresses the importance of understanding its sensitivity and the potential for false positives. “We have to be very cautious with mass adoption of these blood tests because of the potential false positives,” he stated, advocating for a panel of tests to provide a more comprehensive understanding of a patient’s condition.

While new blood tests signify progress, Dr. Isaacson believes that the medical community is still in the early stages of effectively integrating these resources into clinical practice. He remarked, “I feel strongly that we’re in the first inning of a nine-inning baseball game, so to speak.”

As the healthcare landscape evolves with these innovations, experts anticipate that the integration of blood tests will lead to earlier diagnoses and treatment options for patients at risk of Alzheimer’s disease. Dr. Howard Fillit, co-founder and Chief Science Officer at the Alzheimer’s Drug Discovery Foundation, highlighted the significance of these advancements, stating that diagnosing Alzheimer’s earlier with a simple blood test represents a transformative shift in patient care.

With the FDA’s clearance of the Elecsys pTau181 test, Roche Diagnostics is well-positioned to implement this test across approximately 4,500 clinical laboratories in the United States. The ongoing research and refinement of blood-based biomarkers promise to enhance understanding and management of Alzheimer’s disease, potentially leading to better patient outcomes in the future.