Can a Blood Test Help to Diagnose Alzheimer’s?

Soon, Alzheimer’s diagnosis may be worlds easier. We speak with experts on the new wave of diagnostic blood tests, including experts from C2N Diagnostics, the company producing the first-ever Alzheimer’s blood test in use by doctors.

Alzheimer’s is incredibly prevalent, but notoriously difficult to diagnose. Some of the most important information can only be gleaned from expensive and invasive processes, like a brain scan or a spinal tap. But soon, diagnosis may be as easy as getting a simple blood test.


Thanks to cutting-edge research, doctors may soon be able to, just by looking at our blood, determine all kinds of things about our brain health, from our Alzheimer’s risk score to the presence of key blood biomarkers.


“The possibility of early detection and being able to intervene with a treatment before significant damage to the brain from Alzheimer’s disease would be game changing for individuals, families and our healthcare system,” Alzheimer’s Association Chief Science Officer Maria Carrillo said at last year’s annual conference.


To accurately diagnose the pathology of Alzheimer’s disease, a patient currently needs to get a positron emission tomography (PET) scan or a lumbar puncture (also known as a spinal tap) to draw cerebrospinal fluid. Through these methods, doctors can analyze the amount of beta-amyloid plaques and tau tangles in the brain — the hallmarks of Alzheimer’s disease. The problem is, only a small percentage of people diagnosed with early stage Alzheimer’s actually get those tests. Not only are they expensive and not widely available — they are not usually covered by insurance. To solve for this inaccessibility, diagnostic companies are racing to find better solutions, like using just a quick blood draw to reveal more concrete evidence. With better diagnostic methods, doctors can identify risk earlier on so that treatments can happen even before memory loss sets in.


In a major breakthrough last year, C2N Diagnostics, a St. Louis-based biotechnology company in collaboration with researchers from the Washington University School of Medicine developed one of the first Alzheimer’s blood tests, the PrecivityAD test, for 60+ year old people with cognitive impairment who are seeking Alzheimer’s testing. Performed by C2N Diagnostics in its certified lab facility, the test is already available for doctors to use in the clinic, but currently, its not yet approved by the Food and Drug Administration. The test measures proteins in the blood that indicate the probability of amyloid in the brain.


With the PrecivityAD test, patients are assigned a score ranging from zero to 100 and then put into a risk category based on their score range: A value between zero and 36 is “low,” a value between 37 and 57 is “intermediate,” and 58 and above is considered a higher risk for amyloid in the brain.


Dr. Joel Braunstein, CEO of C2N Diagnostics, said risk scores can give a person more information on how susceptible they may be to Alzheimer’s disease. “We think over time, that number’s meaning is going to become even more important, as we get data on repeat sampling in many patients over many years,” he explained.


Researchers hope a higher score may serve as an incentive to adopt more aggressive lifestyle interventions, utilize available therapies or participate in a clinical trial in hopes of dropping that score over time.


Braunstein said that the blood test is a much more viable option for patients to get similar information they would get having a PET scan. “Based on the data that we’ve shared, a score at or below 35, has an 86 percent, negative predictive value for no amyloid in the brain, which means that if you were to then take that patient who had that score and sent them on to a PET scan, 86 percent or more of the time, they will not have a positive scan,” he said.


Meanwhile, other Alzheimer’s blood tests are currently in development. One study out of UC San Francisco is targeting the levels of a protein (pTau181) found in the blood that aggregates in tau tangles in Alzheimer’s patients. Other tests are using artificial intelligence to predict neurodegeneration in blood samples.


Carrillo at the Alzheimer’s Association cautions that research on blood tests for Alzheimer’s is still early and more data needs to be established to determine the accuracy of these tests.

“They need to be tested in long-term, large-scale studies such as Alzheimer’s clinical trials,” she said. “In addition, we need to continue research to refine and verify the tests that are the current state of the art — including cerebrospinal fluid and PET imaging biomarkers.”


But experts like Dr. Marwan Sabbagh, head of the Cleveland Clinic Lou Ruvo Center for Brain Health, says that above all, blood tests are a huge step forward in making Alzheimer’s diagnosis easier.


“The clinical diagnosis accuracy right now is only 70 [to] 75 percent … Study after study after study shows this,” Dr. Sabbagh commented. With the ability to detect the disease’s presence through biomarkers, he speculated that accuracy will rise to “above 90 percent, without having to massively increase the cost of evaluation,” he said. “I think that’s a win, and can be achieved right away.”


Dr. Jeffrey Norton, a principal investigator at Charter Research, a company conducting a clinical trial for C2N Diagnostics, further explained, “Depending on your age, having a negative test might just mean that you have not reached a certain threshold of amyloid in your brain or blood. It’s not a guarantee.”


C2N Diagnostics is currently working with pharmaceutical companies and academic collaborators to better understand how this test behaves in different populations and what it predicts in terms of future outcomes. They are also developing additional biomarkers to hopefully become a part of a brain health panel based on blood testing – akin to getting your cholesterol tested – to be able to better and more easily inform the status of one’s cognitive health.


Dr. Norton believes this blood test is “probably going to turn out to be the first line test you would do when there’s suspicion of dementia.” He added, “The future is looking a little bit brighter, for sure.”


If you or someone you know is interested in participating in a clinical trial of C2N Diagnostics’ new blood test for Alzheimer’s disease pathology, call Charter Research in Lady Lake, Florida at 352-775-1000. Study participants have their memory assessed using certain standardized scales and provide a blood sample. There is no cost to participate, and insurance is not required.


Jeff Pohlig, CEO of Charter Research, added, “It’s incredibly exciting to be on the cusp of a new technology, and we’re thrilled to be conducting this study of C2N’s PrecivityAD blood test for Alzheimer’s pathology. We’re continuing to enroll participants in this study throughout March and into April.”

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