FDA Approves New Blood Test to Assess Alzheimer’s Disease Risk

The US Food and Drug Administration (FDA) has granted clearance to a new blood test designed to assist in assessing the likelihood of Alzheimer’s disease in individuals exhibiting cognitive decline symptoms. The Elecsys pTau181 test, developed by Roche Diagnostics in collaboration with Eli Lilly, offers primary care physicians a tool to identify patients who are unlikely to have Alzheimer’s disease. Those testing positive will be encouraged to undergo further diagnostic evaluations.

This test is specifically intended for adults aged 55 and older in the United States who are displaying signs of cognitive decline. According to Brad Moore, president and CEO of Roche Diagnostics North America, the integration of blood-based biomarker testing into primary care settings can expedite the diagnostic process for patients and their healthcare providers.

The prevalence of dementia is significant, with estimates indicating that over 42% of individuals aged 55 and older in the United States will develop some form of dementia in their later years. Additionally, approximately 92% of adults with mild cognitive impairment remain undiagnosed. Dr. Joanne Pike, president and CEO of the Alzheimer’s Association, emphasized the importance of the test, stating, “This is another important step toward expanding access to Alzheimer’s disease diagnostic tools.”

While the Elecsys pTau181 test assists in ruling out the presence of Alzheimer’s pathology, it is not designed to provide a definitive diagnosis. The test looks for the protein pTau181 in blood plasma, with elevated levels linked to Alzheimer’s and other neurodegenerative diseases. This approach differs from the earlier FDA-cleared Lumipulse G pTau217/ß-Amyloid 1-42 Plasma Ratio test from Fujirebio, which utilizes a ratio of two proteins for detection.

Dr. Richard Isaacson, a preventive neurologist and founder of one of the first Alzheimer’s prevention clinics in the United States, noted the benefit of having multiple tests that assess different biomarkers. He advocates for a comprehensive testing approach rather than relying on a single marker. “We’re not at the time yet where one marker is the ‘be all and end all.’ It’s more complicated than that,” he remarked.

The Elecsys pTau181 test boasts a negative predictive value of 97.9%, meaning that when the test result is negative, there is a high probability that the individual does not have Alzheimer’s-related pathology. Dr. Laura Parnas, director of medical and scientific affairs at Roche Diagnostics, stated, “However, it’s important to note that for patients with a positive result, further clinical investigations and confirmatory testing for the amyloid pathology are needed for the final diagnosis of Alzheimer’s.”

As the medical community integrates these new tools, there are calls for caution regarding the potential for false positives. Dr. Isaacson highlighted the need for more data on the test’s sensitivity and accuracy. He stressed that the adoption of blood tests must be approached carefully, as the medical field is still navigating how best to utilize these results in clinical practice.

The FDA’s clearance of the Elecsys pTau181 test marks a significant advancement in Alzheimer’s diagnostics, following the approval of the Lumipulse test earlier in May. These developments signal a shift toward more accessible and scalable diagnostic tools in Alzheimer’s research. According to Dr. Howard Fillit, co-founder and chief science officer at the Alzheimer’s Drug Discovery Foundation, the ability to diagnose Alzheimer’s through a simple blood test is groundbreaking, akin to cholesterol testing.

As a result of this FDA clearance, Roche has positioned itself to quickly integrate the Elecsys pTau181 test into clinical laboratories across the United States, where approximately 4,500 Roche instruments are already in use. This development holds promise for enhancing early detection of Alzheimer’s disease, potentially leading to timely interventions and improved patient outcomes.

In conclusion, while the Elecsys pTau181 test represents a step forward in Alzheimer’s diagnostics, the medical community remains cautiously optimistic about its implementation and the need for comprehensive testing strategies to ensure the best patient care.