People with memory or thinking changes who are worried they have Alzheimer’s disease can get an answer sooner thanks to a new blood test just cleared by the U.S. Food and Drug Administration (FDA).
The Elecsys pTau181 test, from Roche, can help rule out Alzheimer’s as the cause of cognitive symptoms in adults ages 55 and older. It is the first such test authorized for use in primary care.
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Most people bring memory or thinking concerns to a primary care provider. But until recently, confirming or excluding an Alzheimer’s diagnosis would require a referral to a neurologist and possibly a spinal tap or PET scan.
“Tests like Elecsys are game changers. They expand access to minimally invasive testing for Alzheimer’s and benefit patients to help rule out Alzheimer’s‑related brain changes, reducing the need for costly or invasive follow‑up tests,” says Laurie Sanders, PhD, a researcher and associate professor of neurology at the Duke University School of Medicine in Durham, North Carolina.
How the New Alzheimer’s Test Works
Elecsys measures a blood biomarker associated with Alzheimer’s-type brain changes called phosphorylated tau-181 (p-tau181).
Previous studies have shown that the biomarker p-tau181 can predict the buildup of a protein in the brain called beta-amyloid. So-called amyloid plaques are a hallmark of Alzheimer’s and differentiate the disease from other types of dementia or neurodegenerative conditions.
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Once a primary care doctor decides the Elecsys test is appropriate, they can order a blood sample be sent to a laboratory equipped with Roche testing systems, says Maria-Magdalena Patru, MD, PhD, a scientific partner at Roche Diagnostics.
“The physician will review the results with the patient and discuss next steps for further evaluation or confirmation of diagnosis,” says Dr. Patru.
If the test is negative, Alzheimer’s-related amyloid buildup is unlikely, meaning there may be other conditions causing cognitive decline, says Timothy Chang, MD, PhD, an assistant professor of neurology and a member of the Mary S. Easton Center for Alzheimer’s Research and Care at UCLA in California.
For example, sleep disorders, depression or anxiety, medication side effects, infections, thyroid or vitamin issues, and other types of dementia could all potentially cause cognitive changes.
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It is important to note that a positive result means more information and testing is needed for a final Alzheimer’s diagnosis.
“Patients who test positive can be fast‑tracked and prioritized to receive appropriate confirmatory testing and, if needed, specialty care, and be considered for clinical trials or approved treatments,” says Dr. Sanders, the leader of a research team who created a lab test for Parkinson’s disease.
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How Accurate Is the Test?
The Elecsys was evaluated in a multicenter, noninterventional study of 312 participants representing an “early-disease, low-prevalence” population like primary care.
The test showed a 97.9 percent negative predictive value. That means when the test result is negative, there’s a very high likelihood the person does not have Alzheimer’s disease.
The test is less accurate when it yields a positive result, which is why further assessments are needed in these cases.
How Is the New Test Different From Other Alzheimer’s Blood Tests?
The Elecsys pTau181 is the second blood-based biomarker test to be cleared for Alzheimer’s this year. The FDA cleared the first, known as the Lumipulse G, in May.
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Elecsys looks for only one protein, p-tau181, whereas Lumipulse uses a ratio of two proteins called p-tau217 and beta-amyloid 1-42.
The Elecsys test is slightly better for ruling out Alzheimer’s disease than the Lumipulse G, says Dr. Chang. “This means that a negative Elecsys pTau181 is more likely to mean the individual does not have Alzheimer’s disease pathology,” he says.
How Much Does the Elecsys Test Cost? Will Insurance Cover It?
Roche is actively working with both public and private insurers to establish appropriate coverage and coding pathways, says Patru.
The company expects insurance coverage to “evolve over time” once the test is used more widely and more real world evidence becomes available, says Patru.
“Roche’s goal is to make the test accessible and affordable for as many patients as possible. In the meantime, some physicians may offer it as a self-pay option while reimbursement processes are being established,” she says.
The company hasn’t released price information for the Elecsys test, but the projected cost is reported to be between $500 and $1,000.
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Pricing will vary by laboratory, and it will take time for pricing and coverage to be finalized as laboratories begin offering the test to patients, says Patru.
