What a Newly Approved Blood Test Means for Diagnosing Alzheimer’s
BU researcher and physician Wendy Qiu says the test can help with clinical trials and screening for early cognitive impairment
Lumipulse, the recently approved blood test for diagnosing Alzheimer’s, could help enhance research into the progressive disease—and potentially speed the development of new treatments. Photo via iStock/Mary Long
What a Newly Approved Blood Test Means for Diagnosing Alzheimer’s
BU researcher and physician Wendy Qiu says Lumipulse can help with clinical trials and screening for early cognitive impairment
Even more than a century after it was discovered, much about Alzheimer’s disease still mystifies scientists, like how and why it forms in the first place. But gradual progress in research—including into how certain protein signatures, called biomarkers, can help diagnose different causes of cognitive decline—has helped doctors spot it easier and quicker.
And, now, there’s been a major diagnostic breakthrough: the first Food and Drug Administration–approved blood test for diagnosing Alzheimer’s, the most common type of dementia in the US.
It’s the culmination of years of collaborative international research, according to physician and scientist Wendy Qiu, a Boston University Chobanian & Avedisian School of Medicine professor of psychiatry and pharmacology who studies the causes and signatures of Alzheimer’s. The recently approved test, called Lumipulse and developed by Fujirebio Diagnostics, can help screen for early-stage Alzheimer’s and provide an easier way to monitor clinical trial participants, which could lead to better treatments in the future, says Qiu.
“For patients, this is a big deal,” says Qiu, who coleads the BU Alzheimer’s Disease Research Center’s (BU ADRC) biomarker research core, which manages and analyzes fluid biospecimens and neuroimaging data for the center. “This test will help us differentiate between Alzheimer’s disease and other dementias. Plus, it’s cheaper, effective, and much more acceptable for patients.”
The blood test, which Qiu expects to become a routine part of patient screenings, measures two proteins found in blood plasma—p-tau217 and amyloid beta 42—and then calculates the ratio of them. The ratio of the proteins correlates to the presence of amyloid plaques in the brain, which are key Alzheimer’s signatures, according to the FDA.
Knowing that these proteins are markers of Alzheimer’s is in large part thanks to international research efforts, as well as long-term, nationwide studies, including at the National Institute on Aging–funded BU ADRC. The BU center is one of 35 federally funded Alzheimer’s research hubs in the country, and actively contributes to the Health Outreach Program for the Elderly (HOPE) study, a long-term examination of aging and memory that has over 400 participants. Since 1999, the centers have together compiled one of the world’s largest datasets on Alzheimer’s disease and related dementias.
“Twenty years ago, we didn’t know that p-tau217 and amyloid beta 42 ratio was going to be a diagnostic test,” Qiu says. “I’m glad the NIH [National Institutes of Health] put a lot of effort into collecting samples decades ago. Those samples contributed to the development of this blood test.” BU researchers have also led the way on improving cognitive tests for screening patients and developing potential diagnostic tools—including by using voice recordings and artificial intelligence–powered software to recognize disease patterns.
The Brink spoke to Qiu about the blood test, how decades of research have led to this moment, and what she hopes for the future of Alzheimer’s treatments.
Q&A
with Wendy Qiu
The Brink: Can you explain why having a blood test for Alzheimer’s disease is significant?
Qiu: Different types of blood tests have been used in Alzheimer’s research for years, but this one getting FDA approval is a big deal. A common test we have to do is a lumbar puncture to get cerebrospinal fluid, but patients often don’t want to have the procedure. Even among our research participants, who are very motivated to contribute, less than 20 percent of people get a lumbar puncture. People in the preclinical stage [of Alzheimer’s], who have some cognitive impairment, are even more reluctant to have a lumbar puncture. Another test that was approved by the FDA years ago is the PET [positron emission tomography] brain scan, which is another good test that allows you to directly see brain changes and get amyloid or tau imaging. But it’s very expensive, so there’s no way we can use that consistently. That’s the reason this blood test is a breakthrough for the Alzheimer’s disease field. About 90 to 95 percent of our participants agree to have blood draws—so the cost is less, and people are more willing to accept it.
The Brink: Can you explain the connection between proteins in the blood and the brain?
We know seeing p-tau217—which is a specific type of a phosphorylated amino acid—in the blood is a signature of Alzheimer’s disease in the brain. Another signature is amyloid beta 42. How these proteins come out of the brain and get into the blood, that mechanism is not clear. It could be through the blood-brain barrier, because we know the blood-brain barrier in brains with Alzheimer’s is broken.
The Brink: What are we able to learn from the ongoing HOPE study at BU ADRC?
It’s really a treasure to store these samples for research purposes. We receive biofluid samples from more than 400 participants recruited from a community of people interested in contributing to research. They come to BU ADRC annually to get blood draws and neuroimaging. We do consensus diagnosis meetings every week, where different cases are presented to neurologists, psychiatrists, neuropathologists, and radiologists. Now we’re going to have the Lumipulse blood test as part of the clinical cases, along with imaging, cognitive tests, medical history, and other factors. This will help us diagnose and do differential diagnosis—for example, in CTE [chronic traumatic encephalopathy] patients, they have p-tau, but not amyloid. We don’t have biomarkers or tests for people living with CTE, but with this test, we can tell if they have Alzheimer’s, or they don’t. We also rely on clinical history, like if the patient has been in an accident, or if they’re a veteran, or have had a brain injury or falls, to make those decisions.
Storing these samples and the data we draw from them is very valuable, because we check their cognition every year, so over time, we can see the differences between people who have declined, or developed Alzheimer’s disease, and people who stay healthy cognitively. My colleague Rhoda Au is a leader in developing digital cognitive tests, another aspect of the field that has advanced very fast. In the past, the cognitive test took about four hours and had to be done in a clinic, so a lot of older patients could not tolerate that. Now, with digital tests that can be done from home, it’s much faster and we get more detailed information.
The Brink: Why is it so difficult to treat dementia, including Alzheimer’s disease—and are you hopeful it will improve?
More than 90 percent of clinical trials for Alzheimer’s disease [treatments] have failed, even after passing phase two, so that’s a major challenge. We still have a large number of patients who we cannot treat effectively yet. One advantage of this blood test is that it makes it easy to monitor patients in clinical trials: we cannot spinal tap patients every three months, but we can do a blood draw. This will help in finding good treatments. Currently, available treatments are very expensive, and mainly target amyloid beta protein. There are drugs that also target tau, but they are not successful yet. So, we’re still in the process of finding different drug targets. I see the field moving very fast, and I’m confident that in 5 to 10 years, we’re going to have good drugs for treatment.
This interview has been edited for length and clarity.
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