Amyloid PET positivity differs across dementia groups

A Vanderbilt Health-led study found lower amyloid PET positivity among Black and Hispanic Medicare beneficiaries with mild cognitive impairment or dementia compared with all other racial and ethnic groups. The findings were reported May 27 in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association.

The analysis included 5,757 Medicare recipients from across the U.S. with cognitive impairment. Vanderbilt described it as one of the largest PET brain-imaging studies to date examining ethnoracial differences among people with cognitive impairment.

Black participants accounted for 22% of the cohort, Hispanic participants for 20%, and the remaining 58% were grouped as all other races and ethnicities. The study assessed amyloid PET positivity and nonmedical drivers of health, including gender, education, Medicare coverage type, and Area Deprivation Index.

Compared with all other races and ethnicities, odds of amyloid positivity were 28% lower among Black participants and 22% lower among Hispanic participants. Black and Hispanic participants were also more likely to present at the dementia stage rather than with mild cognitive impairment.

Enrollment patterns differed by coverage type. Vanderbilt said Black and Hispanic participants were more than twice as likely to be enrolled in Medicare Advantage plans, which the authors linked to access-to-care barriers.

Neighborhood-level socioeconomic status also showed an association. Odds of amyloid PET positivity were 22% higher in comfortable Area Deprivation Index groups and 40% higher in distressed groups compared with prosperous areas, while mid-tier and at-risk areas did not significantly differ from prosperous areas.

No significant differences in PET positivity odds were found across gender, educational attainment, or type of Medicare coverage. The authors said social determinants of health did not fully explain the ethnoracial differences in amyloid positivity.

Amyloid plaques are a hallmark of Alzheimer’s disease, which accounts for 60%-80% of dementia, Vanderbilt noted. Patients with other causes of dementia may not show amyloid plaque pathology on PET imaging.

“Normal PET results may lessen treatment access and clinical trial eligibility,” said first author Corey Bolton, PsyD, assistant professor of geriatric medicine at Vanderbilt. He said the study suggests those disadvantages may fall disproportionately on Black and Hispanic patients.

Funding came from the Alzheimer’s Association, American College of Radiology, Avid Radiopharmaceuticals, GE HealthCare, Life Molecular Imaging, and the National Institutes of Health, according to Vanderbilt.