• Posted April 19, 2024

One Neurological Factor Keeps Black, Hispanic Patients From Alzheimer's Clinical Trials

Black and Hispanic patients with Alzheimer's disease are greatly underrepresented in clinical trials, even though they're more likely to get dementia than whites.

However, racial discrimination may not be driving this disparity, a new study finds.

Instead, Black and Hispanic people are being judged ineligible for Alzheimer's trials because they appear to have lower levels of brain amyloid buildup in the early stages of the disease, researchers reported April 17 in the journal Alzheimer's & Dementia.

"In these early stages, we see that the amyloid levels are different across racial and ethnic groups. That may be an important contributor to the underrepresentation of some groups in amyloid-lowering trials,"said lead researcher Doris Molina-Henry, an assistant professor of research neurology with the Alzheimer's Therapeutic Research Institute at the University of Southern California's Keck School of Medicine.

Amyloid beta brain plaques are considered one of the hallmarks of Alzheimer's. In fact, new Alzheimer's drugs are designed to lower a person's amyloid protein levels.

But this study shows that more than just amyloid may be responsible for Alzheimer's and other dementias.

"This opens up further questions: 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?"Molina-Henry said in a university news release.

For this study, researchers collected blood tests and brain scans from more than 4,900 participants ages 55 to 80 who were trying to get into a clinical trial to test Leqembi (lecanemab), the first drug to receive FDA approval to treat Alzheimer's.

None of the participants had any impairment characteristic of Alzheimer's and dementia, but some did have some biological changes related to these diseases, researchers said.

In particular, the trial's design required that the patients have a minimum blood level of amyloid protein.

Of the patients tested, 35% met the amyloid cutoff required to be in the study.

But Black, Hispanic and Asian people were significantly less likely to meet the eligibility criteria for the Leqembi trial, results show.

Whites had the highest rate of eligibility at 39%, researchers found, compared to 25% of Black and Hispanic people and 21% of Asian people.

Brain scans looking at amyloid deposits in the brain showed that all of the people included in the trial based on the blood test deserved to be there, researchers found.

"This suggests that 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.

Research now needs to investigate whether factors other than amyloid  -- like heart disease, high blood pressure, excess weight or inflammation -- could be increasing the risk of dementia in different racial and ethnic groups, the study concluded.

The results also highlight the need for better screening to detect dementia and Alzheimer's early, Molina-Henry said.

"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,"Molina-Henry said. "Contributing to research in this way adds critical diversity and helps us answer questions about this very devastating disease."

More information

Yale School of Medicine has more about lecanemab.

SOURCE: University of Southern California, news release, April 17, 2024