Despite the increased risk of Alzheimer’s disease, African Americans and Hispanics are underrepresented in clinical trials. A recent USC study finds that some racial groups are underrepresented in Alzheimer’s studies, and that’s simply because they don’t qualify.
Researchers from the Keck School of Medicine at USC studied blood tests and brain scans from 4,905 people aged 55 to 80.
These tests find levels of amyloid, a marker for Alzheimer’s disease. Black people have lower levels of detectable amyloid.
Participants who identified as non-Hispanic white were more likely to qualify for clinical trials. This was in comparison to other racial groups.
According to Doris P. Molina-Henry, PhD, assistant professor of research neurology at the Alzheimer’s Therapeutic Research Institute (ATRI) at the Keck School of Medicine and lead author of the study, these findings may contribute to the lack of representation in trials aimed at lowering amyloid levels.
Molina-Henry feels that the prevalence of low amyloid levels in Black people opens up a host of questions regarding the development of Alzheimer’s disease. She says, “If it’s not amyloid that’s driving Alzheimer’s disease, what is it? Or if amyloid is driving this, what is making the brain of someone from a group at higher risk for dementia much more susceptible?”
The study clinically tested a new drug, and the research team at Keck sought to recruit and enroll diverse, preclinical patients, especially people traditionally underrepresented in Alzheimer’s studies. The participants included: 60 Hispanic Blacks, 671 Hispanic whites, 101 non-Hispanic Asians, 381 non-Hispanic Blacks, and 3,692 non-Hispanic whites.
Of the 4,905 people tested, 1,724 (35.1 percent) were eligible to participate in a clinical trial. Of those who met the criteria for the study, only 13.3 percent of Hispanic Blacks and 24.7 percent were non-Hispanic Blacks.
The difference shows why Black people are less likely to be diagnosed with Alzheimer’s and other dementias. They are 35 percent less likely to receive these diagnoses. However, this does not give the whole picture.
This difference in Alzheimer’s rates among Black Americans and Latinos needs more research. These groups are at a higher risk of developing the disease. Because of the lower levels of amyloid, participants in the study were only considered preclinical. That means that they lacked the typical mental impairment characteristics associated with Alzheimer’s disease or other forms of dementia.
However, they did have biological signs that are linked to amyloid deposits (amyloid buildup). They might be candidates for clinical trials. These trials aim to help in the early stages. They do this by either removing amyloid protein from the brain or stopping it from building up.
“The cutoffs for eligibility are adequate but also point to a paradox where some groups may have a higher risk of dementia but lower levels of amyloid, and treating those groups may require a different approach,” Molina-Henry said.
Black people are more likely to have severe cognitive impairments and symptom severity than white participants. This could be increased by risk factors that are more prevalent among Black people. The Alzheimer’s Association says that some conditions can harm blood vessels. These include heart disease, diabetes, strokes, and high blood pressure. These conditions may raise the risk of dementia.
These are all medical conditions that run rampant in the Black community and are less likely to be under control. Additionally, individuals who have a family history of Alzheimer’s or dementia are at an even higher risk.
There is also a geographic component: research has found that individuals who live in the South have a higher prevalence of dementia-related conditions. This is partly because of environmental and socioeconomic factors. These include limited access to healthcare, higher poverty rates, and more chronic diseases.
Beyond Alzheimer’s disease, other forms of amyloidosis can impact overall health and contribute to cognitive decline. AL amyloidosis and AA amyloidosis are two common types of amyloidosis, conditions caused by abnormal protein deposits in organs and tissues. Amyloid deposits can contribute to organ dysfunction and, in some cases, neurological issues.
AL amyloidosis primarily affects the heart, kidneys, liver, and nervous system, while AA amyloidosis is often linked to chronic inflammatory diseases. Symptoms such as shortness of breath, swelling, and fatigue can indicate the presence of these conditions. While they are different from Alzheimer’s, studying amyloidosis in diverse populations may provide further insight into how amyloid proteins interact with different biological systems.
Black people are underrepresented in most clinical trials, and Molina-Henry hopes for an increase. “More than ever—particularly for groups who are underrepresented in research—it’s important to participate in screening efforts, to have your blood drawn and, if eligible, to join a clinical trial,” she says. “Contributing to research in this way adds critical diversity and helps us answer questions about this very devastating disease.”
In the meantime, individuals can take steps to reduce their risk of Alzheimer’s and dementia by maintaining a heart-healthy lifestyle, controlling blood pressure, staying physically active, and getting regular medical checkups. Identifying and managing risk factors for dementia can play a crucial role in slowing its progression and improving overall brain health. While some side effects of clinical trial treatments are still being studied, expanding research participation is essential to finding more effective solutions for everyone.
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