New Blood Test May Forecast Alzheimer’s Symptoms Years in Advance

A simple blood draw may soon help answer one of the most difficult questions in Alzheimer’s disease: When will symptoms start? In a study published in Nature Medicine, researchers report that levels of a specific protein in the blood can help estimate when a person is likely to begin experiencing cognitive symptoms of Alzheimer’s. Using long-term data from hundreds of older adults, the team built models that predicted symptom onset within roughly three to four years.

The findings suggest that a relatively accessible blood test could help identify people who are still cognitively healthy but biologically on the path toward Alzheimer’s, potentially reshaping how prevention trials are designed.

“Our work shows the feasibility of using blood tests, which are substantially cheaper and more accessible than brain imaging scans or spinal fluid tests, for predicting the onset of Alzheimer’s symptoms,” said senior author Suzanne E. Schindler in a press release.

Read More: Alzheimer’s Disease Blood Test Could Lead to Earlier, More Effective Treatment

The Protein That Tracks Alzheimer’s Progression

The study centers on a protein called p-tau217, which circulates in blood plasma. Previous research has shown that p-tau217 levels rise as two hallmark Alzheimer’s proteins — amyloid and tau — accumulate in the brain.

Amyloid plaques and tau tangles begin forming years, even decades, before memory problems emerge. Like rings forming in a tree trunk, these proteins build up in a fairly predictable pattern over time. The more that accumulate, the further along the disease process tends to be.

Until recently, detecting those changes required expensive brain scans or invasive spinal taps. Blood-based tests for p-tau217 offer a simpler way to track those shifts.

To understand how blood levels relate to symptom timing, researchers analyzed data from 603 adults enrolled in two long-running Alzheimer’s research programs.

By tracking p-tau217 levels over time and comparing them to when cognitive symptoms appeared, the team developed models linking elevated protein levels to the likely age of symptom onset.

When p-tau217 rose earlier in life, symptoms tended to appear decades later. When the protein increased at older ages, the window between biological change and cognitive decline was shorter.

For example, individuals with elevated levels at age 60 developed symptoms roughly 20 years later. Those whose levels rose at age 80 developed symptoms closer to 11 years later.

Why Timing Matters

Alzheimer’s affects more than seven million Americans, and while treatments can ease symptoms for some patients, no therapy currently prevents the disease. One of the biggest challenges in developing preventive treatments is identifying people who are biologically at risk but not yet showing signs of memory loss. Clinical trials often take many years, partly because researchers must wait for symptoms to appear.

If researchers can more accurately estimate when symptoms are likely to begin, they may be able to enroll participants at the right stage, making trials shorter and more efficient.

The researchers also tested their model across different p-tau217 blood tests and found similar results, suggesting the approach may work beyond a single proprietary platform.

A Future of Earlier Insight

The team has made its modeling tools publicly available so other researchers can refine and expand them. Additional blood-based biomarkers may further improve accuracy in future studies.

While the idea of predicting symptom onset may feel daunting, experts say the goal is not to alarm patients, but to prepare them.

“In the near term, these models will accelerate our research and clinical trials,” Schindler said. “Eventually, the goal is to be able to tell individual patients when they are likely to develop symptoms, which will help them and their doctors to develop a plan to prevent or slow symptoms.”

This article is not offering medical advice and should be used for informational purposes only.

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Article Sources

Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:

• This article references information from a recent study published in Nature Medicine: Predicting onset of symptomatic Alzheimerʼs disease with plasma p-tau217 clocks