Blood tests may have an edge spotting Alzheimer's
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There's growing evidence that blood tests can accurately diagnose Alzheimer's disease and pave the way for earlier treatment of more patients.
Why it matters: Making Alzheimer's easier to detect is seen as crucial now that new drugs that slow the disease's progression are coming onto the market.
- A blood test has advantages over pricey PET scans or more invasive spinal taps that are now used to diagnose the dreaded neurological condition and could be incorporated into routine physician office visits.
Driving the news: A study featured at an international Alzheimer's conference this week in Philadelphia showed that blood tests allow primary care doctors to accurately detect the characteristics of Alzheimer's.
- There are at least 16 blood tests in development, though none has won FDA approval yet.
- Primary care is "the first, and in many cases, the final point of entry for these patients," said study co-author Sebastian Palmqvist, an associate professor at Lund University in Sweden. "Looking at the future, I think this is where the blood test can have the largest impact."
- Doctors in the study used a blood test made by C2N Diagnostics, which performs as well as an FDA-approved spinal fluid test for detecting molecular signs of Alzheimer's.
Zoom in: Until recently, it's been hard to know for sure if a person suffering from cognitive impairment had Alzheimer's.
- But because new approved treatments appear to work best on patients with early stages of the disease and mild symptoms, there's urgency around getting a quick diagnosis.
- PET scans can cost thousands of dollars and are often only available at large academic medical centers, and patients can be hesitant to do spinal taps, said George Vradenburg, founding chairman of the Davos Alzheimer's Collaborative.
The blood test assessed the buildup of proteins in the brain thought to contribute to Alzheimer's.
- Primary care doctors and dementia specialists used the test to screen for pathological signs of Alzheimer's with 91% accuracy, per the study, published Sunday in JAMA.
- That's compared to 61% success rate using clinical evaluations like cognitive testing in a primary care setting and 73% by dementia specialists using the same tools.
- The research covered 1,213 patients examined for cognitive symptoms in Sweden between 2020 and 2024.
Context: Alzheimer's affects nearly 7 million Americans and diagnoses are expected to almost double by 2050.
- The latest treatments target proteins known as amyloid plaques that are believed to contribute to the development of the condition. A second protein called tau can get tangled in the brain and is believed to lead to cognitive decline. By lowering amyloids, the drugs can slow the spread of tau.
- "Now that we have treatments that work best when they're started early, it adds a sense of urgency to diagnosis that was never there before," said Suzanne Schindler, another author of the new JAMA paper.
- Getting an appointment with a dementia specialist can take weeks, if not months. "With these blood tests, we could potentially decrease the amount of time that it takes from when patients develop symptoms to when they're diagnosed," said Schindler, a neuroscientist at Washington University in St. Louis.
Yes, but: The accuracy of blood tests for Alzheimer's can vary widely, and many clinicians are still skeptical of them.
- Arjun Masurkar, a dementia and Alzheimer's specialist at NYU Langone, said he sees blood tests as "very exciting," but he doesn't use them in clinical practice yet.
- "They're not truly ready for prime time just yet," Masurkar said, noting even if he wanted to use them, New York has restrictions on the tests.
- The FDA's recent — and controversial — decision to increase regulatory oversight of lab-developed tests could make clinicians more likely to trust and use appropriate blood tests to detect Alzheimer's biomarkers, Schindler said.
What we're watching: Though no Alzheimer's blood tests have FDA approval yet, multiple have been designated as "breakthrough devices," which earns them prioritized review of regulatory submissions.
- The Alzheimer's Association has asked experts to update clinical practice guidelines on how to use blood tests with an eye toward releasing recommendations in early 2025, senior director of scientific engagement Rebecca Edelmayer told Axios.
