Within America AD is among the top 6 leading causes of death, with over 5 million people being affected and the prevalence of the disease is increasing. Diagnosing AD is notoriously difficult, with the process requiring brain scan technology which can be expensive and inaccessible.
An approach to tackling these challenges and gaps may be the development of a blood test for the disease. Several different tests have been in the development stages over the past years, with many designed to detect key biomarkers such as beta-amyloid and tau protein in the brain via blood plasma. But most of these tests are still years from completion.
Not surprisingly it comes as big news when one of these experimental tests becomes available on the market in most states in America and in Europe. This test developed by C2N Diagnostics by researchers from Washington University School of Medicine joins an existing Quest Diagnostic blood test designed to identify biomarkers for the disease, but this test is not widely used which is impart due to questions of accuracy.
The recent C2N test is specifically designed for those aged 60+ who are experiencing cognitive impairment, and who are accordingly seeking testing for Alzheimer’s disease. Not cheap, this test called PrecivityAD cost $1250, but still significantly cheaper than more expensive amyloid PET scans that typically will not have insurance coverage. Unfortunately, at this time this blood test is not covered by most insurance, but according to a CBS report, the company is offering income-based discounts. Only doctors can order this test, results should be delivered within 10 days.
Notably, the company has not published any of their data on the accuracy of this test, though promotional materials are comparing the accuracy rates to that seen with PET scans. This paired with the test not being FDA approved is raising a few red flags.
According to CBS:
“Independent experts are leery because key test results have not been published and the test has not been approved by the U.S. Food and Drug Administration — it’s being sold under more general rules for commercial labs. But they agree that a simple test that can be done in a doctor’s office has long been needed.”
“I think there are two key steps that need to happen before this test really becomes more widespread,” internal medicine specialist Dr. Karen Abrashkin said on CBSN Tuesday. “One is that we need to see the data that’s being used to develop the test. We haven’t seen that data yet. It hasn’t been published and so we don’t know how sensitive or specific this test is for Alzheimer’s.”
The other, according to Abrashkin, is FDA clearance. “That’s really a stamp of approval that needs to happen before the test becomes more widespread,” she said.”
Dr. Eliezer Masliah, neuroscience chief at the U.S. National Institute on Aging, said the government-funded some of the work leading to the test as well as other kinds of blood tests. “I would be cautious about interpreting any of these things,” he said of the company’s claims. “We’re encouraged, we’re interested, we’re funding this work but we want to see results.”
Alzheimer’s disease blood tests will not be endorsed by the Alzheimer’s Association until it has FDA approval, says the vice president of Medical & Scientific relations Heather Snyder, who also suggests that the test needs to undergo trials among larger and more diverse populations. “It’s not quite clear how accurate or generalizable the results are,” she said.
Others are more optimistic about the test, such as Dr. Marwan Sabbagh who is a leading investigator for many national AD prevention and treatment trials at the Cleveland Clinic. “[C2N’s] test is going to have great accuracy,” he said. “I think that’s the first-gen blood test … and I think over time we will see more and more tests added.”
