A new study is shedding light on why some of the people most at risk for Alzheimer’s disease are missing from clinical trials.
Researchers from the Keck School of Medicine at the University of Southern California found that individuals from racial and ethnic groups with higher risk of dementia—such as African American, Hispanic, and Asian populations—are less likely to show early signs of Alzheimer’s in their blood.
These signs are needed to qualify for trials of certain treatments.
This discovery focuses on a blood test that looks for a marker called p-tau217.
This marker is strongly linked to the buildup of amyloid, a harmful protein that collects in the brain years before symptoms of Alzheimer’s begin.
The p-tau217 test helps researchers decide who is eligible to take part in trials testing new Alzheimer’s treatments, such as lecanemab, which aims to remove amyloid from the brain.
In this study, people from African American, Hispanic, and Asian backgrounds were found to have lower levels of p-tau217, meaning they were less likely to show early amyloid buildup and didn’t qualify for the trial.
This raises important questions: If these groups have a higher overall risk of dementia, why don’t they have higher levels of amyloid?
The study included more than 6,400 adults, ages 55 to 80, from across the U.S. All participants were mentally healthy when they joined the study.
Blood tests showed that non-Hispanic white people were more likely to have p-tau217 levels high enough to qualify for the trial. People from other racial and ethnic groups were significantly less likely to qualify.
To further check, researchers also looked at PET brain scans to measure amyloid buildup directly. Among those who had high p-tau217 levels, all groups were equally likely to show amyloid in their brain scans.
This means the blood test itself works across all groups. However, fewer people from minority backgrounds reached that qualifying level in the first place.
Dr. Doris Molina-Henry, the lead researcher, explained that this might not be a problem with the test, or with how people are recruited for trials.
It could mean that amyloid just isn’t the main reason these groups get dementia. She said, “If amyloid is not what drives disease risk in these groups, then we need to do our due diligence to find out what does.”
To better understand this, people who didn’t qualify for the main trial were invited to join another study called APEX. This study will follow their health over time and track other signs in their blood that could predict Alzheimer’s risk.
This study is one of the largest to use blood tests instead of brain scans to find early signs of Alzheimer’s in healthy people. Blood tests are easier, cheaper, and less invasive than brain scans, and they could help doctors and researchers learn more about who is at risk.
These new findings suggest that diversity problems in Alzheimer’s research may not be caused by lack of interest or poor outreach, but by biological differences in how the disease starts. That’s why future research needs to explore other causes of dementia, especially for high-risk groups.
Next, the researchers plan to analyze data from over 20,000 people screened for Alzheimer’s trials worldwide. They hope to better understand how Alzheimer’s develops in different populations and how to create treatments that work for everyone.
If you care about Alzheimer’s, please read studies about Scientists find the root cause of Alzheimer’s disease and findings of Alzheimer’s might not be primarily a brain disease. A new theory suggests it’s an autoimmune condition.
For more about Alzheimer’s disease, please read studies about These places in U.S. have the most cases of Alzheimer’s disease and findings of Scientists confirm the link between COVID-19 and Alzheimer’s disease.
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