The two drugs — Leqembi and donanemab — are the first to offer real hope of slowing the fatal disease for the 6.5 million Americans living with Alzheimer’s.
Groundbreaking Alzheimer’s treatments, including Leqembi and donanemab, which work by targeting the toxic protein beta amyloid, may not be as effective for Black patients as they are for white Americans. According to Alzheimer’s experts, Black patients may have a different disease pathology, and the exclusion of Black individuals from clinical trials has raised concerns about the broader applicability of these treatments.
Both Leqembi and donanemab have shown promising results in slowing cognitive decline, but there is a significant disparity in their clinical trial participation. Older Black Americans are twice as likely to have dementia as their white counterparts, yet they were screened out of these trials at a higher rate due to lower levels of amyloid, a defining marker for Alzheimer’s. While Hispanics were also excluded at a somewhat higher rate, the issue was notably more severe for Black patients.
This growing concern about the amyloid disparity is prompting questions about whether these drugs will have the same impact across all demographic groups. Experts such as Dr. Crystal Glover are questioning whether the drugs are truly applicable to the populations most at risk, given that they were designed with amyloid as the primary indicator for Alzheimer’s.
With Alzheimer’s disproportionately affecting older Black Americans, who have a dementia rate twice that of whites, there is increasing concern about the clinical trial criteria. These trials have excluded a significant number of Black participants, creating an underrepresentation of this group despite the high prevalence of the disease among them. Black people represent 13.7% of the U.S. population but only 4.5% of the participants in the U.S. portion of Leqembi’s trial.
Researchers are now exploring whether Black patients are experiencing dementia due to factors beyond amyloid, such as other health conditions common in the population. This could suggest that the underlying causes of dementia might differ in Black Americans compared to white patients, which raises concerns about the treatments’ efficacy.
Both the FDA and Eisai are aware of this disparity and are working to address it. Eisai is collaborating with the NIH to explore the effectiveness of Leqembi in individuals with elevated amyloid levels but without cognitive decline. The company is aiming for at least 8% Black enrollment in the ongoing trials but is finding it challenging, as 95%-98% of Black candidates do not meet the amyloid threshold for inclusion.
The FDA has acknowledged the issue and encourages more inclusive trial participation, but the long-term implications of this disparity are still unknown. As Leqembi and other treatments continue to develop, it remains to be seen how they will address the specific needs of diverse populations and whether they can effectively slow Alzheimer’s disease across all ethnic groups.
