What Alzheimer’s Biomarkers Reveal in Black and Hispanic Americans

Despite having a higher risk of developing Alzheimer’s, Black and Hispanic individuals have long been underrepresented in the research shaping the modern understanding of Alzheimer’s. 

The groundbreaking work in understanding how the disease progresses, which biomarkers are linked to cognitive decline, and which treatments work has been conducted on predominantly white participants. 

To close this knowledge gap, Sid O’Bryant, professor of pharmacology and neuroscience at the University of North Texas, is running the Health & Aging Brain Study – Health Disparities (HABS-HD). It’s the most comprehensive study of Alzheimer’s biomarkers ever conducted in a diverse population, including 1,500 participants each who are Black, Hispanic, and non-Hispanic white over age 30. 

HABS-HD recruits from within the community rather than speciality neurology centers, welcoming those with co-existing medical conditions like high blood pressure or kidney disease who would be excluded from other research — making it more reflective of the real world population. The data is also made available for other scientists to analyze and build upon.

At the AD/PD 2026 conference in Copenhagen, O’Bryant shared new findings strengthening the evidence that Alzheimer’s may not follow a single pathway of progression, especially in Black and Hispanic individuals. 

“For some people, tau is going to be a very powerful driver of cognitive loss, for other people it may be their diabetes,” O’Bryant told Being Patient.  

Rethinking the biological progression of Alzheimer’s

Alzheimer’s specialists developed the A/T/N framework to describe the progression of the disease which follows a defined sequence: first A, amyloid, builds up decades before symptoms, followed by T, tau tangles, that lead to N, or neurodegeneration and cognitive decline. 

But data from HABS-HD shows the pattern doesn’t always hold. Even among white participants, tau isn’t always the main driver of cognitive decline, sometimes it’s diabetes. The differences are more pronounced among other ethnicities. 

“When looking at Hispanics and blacks, tau was not the primary driver of cognitive loss,” O’Bryant said. “It was vascular issues as well as neurodegeneration.”

The study also considers other sociodemographic factors including education, income, reading level, and access to health care. 

Lower socioeconomic status and living in neighborhoods with high levels of socioeconomic deprivation are emerging as stronger drivers of cognitive decline among Hispanic and Black individuals in the study. 

“These underrepresented communities are more likely to live in areas of greater deprivation,” said O’Bryant. 

These populations also experience higher rates of diabetes, chronic kidney disease, and high blood pressure which may affect Alzheimer’s biomarker levels and disease progression.   

Rethinking Alzheimer’s trials

The field is shifting toward preventing Alzheimer’s disease. To figure out who’s at risk for developing it, researchers have traditionally used biomarkers to look for beta-amyloid plaques in the brain. If the level of plaques surpasses a certain threshold, a person may be considered at risk of developing the symptoms of Alzheimer’s in the near future. 

But the field may need to rethink this concept. 

“The notion of positivity really is more of an older concept that we need to get beyond,” said O’Bryant. “Amyloid levels below a positivity threshold actually still increase risk for future decline over time.”

Understanding these biomarkers across a broader, more representative population could help researchers tailor treatments more effectively. “Once we’ve removed amyloid, where do we need to go next? That’s where the field’s headed,” he said.. 

In the future, combination treatments — anti-amyloid plus GLP-1 or anti-amyloid plus anti-tau — could form a new model of personalized care that targets the individual drivers of cognitive decline. 

While HABS-HD recruited a large diverse population, many drug companies and researchers still struggle to do the same. O’Bryant said that he uses outreach within the community to reach people who would never otherwise see a neurologist. Based on HABS-HD research, he argues that lowering this screening threshold would mean more Black and Hispanic individuals are included without substantially raising study costs.

 “My communities that I serve want access to trials,” O’Bryant said. “We can’t wait for the community to come to us.”