New IDEAS study finds striking racial and ethnic differences in amyloid PET positivity.

A new, targeted study finds major differences in Alzheimer’s-related brain changes among certain racial and ethnic groups, signaling how disparities could affect access to vital treatments.

Results published in JAMA Neurology show Asian, Black and Hispanic participants had significantly lower levels of amyloid detectable via PET brain scans when compared with white participants with similar levels of cognitive impairment.

Despite experiencing elevated rates of Alzheimer’s and related dementias, marginalized groups including Black and Hispanic individuals have historically been omitted from research into disease etiology.

“There are far-reaching implications on the patients and their families.”

Consuelo Wilkins, M.D., first author of the study and a professor of medicine and senior vice president for health equity and inclusive excellence at Vanderbilt University Medical Center, said lower levels may cause patients to fall short of treatment thresholds for existing therapeutics.

“There are far-reaching implications on the patients and their families,” Wilkins said, adding that treatments designed to target brain amyloid may also be less effective for these populations.

Focused Analysis

The analysis is a second-layer investigation involving results from the Imaging Dementia-Evidence for Amyloid Screening (IDEAS) study that began nearly a decade ago. New IDEAS, as it’s known, unites researchers in evaluating the clinical utility of PET scans, specifically among minoritized populations.

Wilkins and colleagues whittled down the IDEAS cohort to those with PET scan data that could be matched appropriately to their counterparts. In total, they matched 313 Asian, 615 Black and 780 Hispanic participants 1:1 to white counterparts by age, sex, education, living arrangement, and level of cognitive impairment – plus a personal or family history of diabetes and a personal history of hypertension.

“These populations have higher rates of diabetes and hypertension, which are associated with vascular diseases of the brain,” Wilkins explained.

The researchers found Asian, Black and Hispanic participants were less likely to have a positive amyloid PET scan as compared to white participants. Asian and Hispanic participants also had a lower overall proportion of amyloid PET positivity. Given participants were matched based on clinical symptoms and demographic factors, the researchers say their results “may reflect differences in the etiology of cognitive impairment.”

Added Wilkins, “Our findings illustrate the urgency of understanding the underlying causes of memory loss in racially and ethnically diverse communities.”

Look Beyond Amyloid

Amyloid in the brain has been a de facto biomarker for Alzheimer’s for decades. Many medications target brain amyloid, including the latest FDA approvals, monoclonal antibodies aducanumab and lecanemab. A third antibody, donanemab, is also expected to receive approval, Wilkins said.

Wilkins and colleagues note that clinical trials supporting FDA approval of these drugs overwhelmingly enrolled white participants. The trials also used PET scans to measure drug efficacy, at least in part. The new study makes it difficult to extrapolate their potential benefit across racial and ethnic groups, say the researchers.

“If diverse groups are less likely to benefit from amyloid-directed therapies and likely to experience considerable financial hardship from the associated cost, there is a risk these novel treatment options may exacerbate existing racial and ethnic disparities in dementia care,” they wrote.

Progress Through Research

Wilkins, who is also an associate director for the Vanderbilt Memory and Alzheimer’s Center, says she is glad to see growing interest in large-scale studies like New IDEAS that focus on historically marginalized populations.

“The impact of Alzheimer’s disease is on a growth trajectory in the coming years. Understanding the biological underpinnings of the disease, and the different ways it starts and develops is central to finding effective therapies,” she said.

Wilkins remains steadfast in her commitment to understanding such distinctions, though progress can feel slow.

“My entire career has been dedicated to understanding and mitigating health disparities, which have become intractable in the United States,” Wilkins said.

She spearheads the Southeast Collaborative for Innovative and Equitable Solutions to Chronic Disease Disparities and was recently appointed to the National Academies of Sciences, Engineering and Medicine committee on a panel titled “Unequaled Treatment Revisited,” which centers around the landmark Institute of Medicine report that highlighted challenges faced by people of color navigating health care. She says many of the challenges persist.

“The original report provided evidence-based recommendations for policy, legal, regulatory and health systems interventions to address disparities. The uptake and implementation of these recommendations has varied, which has limited progress,” Wilkins said.

About the Expert

Consuelo H. Wilkins, M.D.

Consuelo H. Wilkins, M.D., M.S.C.I., is a professor of medicine, senior vice president and senior associate dean for Health Equity and Inclusive Excellence at Vanderbilt University Medical Center. A national thought-leader in addressing the elimination of systemic inequities, she has pioneered new approaches to engaging vulnerable, socioeconomically disadvantaged, and marginalized populations.