​Older Asian, Black, and Hispanic adults with dementia and mild cognitive impairment (MCI) have a lower chance of having a positive amyloid PET scan than their non-Hispanic White counterparts, according to a study published online Oct. 3 in JAMA Neurology.

“Racial and ethnic differences found in amyloid PET positivity among individuals with MCI and dementia in this study may indicate differences in underlying etiology of cognitive impairment and guide future treatment and prevention approaches,” explained lead author Consuelo H. Wilkins, MD, MSCI, of the division of geriatric medicine at Vanderbilt University Medical Center in Nashville, TN, and colleagues.

According to the study, the number of AD cases is expected to almost triple over the ensuing decades, and Hispanic and Black people are 1.5 to 2 times more likely to have clinical AD or related dementias (ADRD) than other racial and ethnic groups. (Asian Americans, meanwhile, “may have lower age-adjusted incidence of all-cause dementia,” researchers added.)

“The increased risk of ADRD among Black and Hispanic individuals may be driven by dementia risk factors, including rates of cardiovascular disease and diabetes, as well as social and structural factors (e.g., lived experiences of discrimination and racism, economic opportunity, neighborhood disadvantage, and access to quality education),” the study noted.

Delayed diagnosis and misdiagnosis of AD, lack of access to dementia specialists, and biases in neuropsychological testing also can exacerbate disparities in AD and dementia and affect minorities, researchers added. They said that racial and ethnic groups with higher rates of clinical AD “are underrepresented in studies of AD biomarkers,” including amyloid PET, and they questioned whether rates of positive amyloid PET differed among people in those groups who have MCI or dementia.

Their multisite, practice-based study involved data from the Imaging Dementia—Evidence for Amyloid Scanning (IDEAS), a single-arm cohort study of Medicare beneficiaries enrolled at 595 US-based dementia specialist practices. The participants underwent amyloid PET imaging from February 2016 to September 2017 with follow-up occurring through January 2018. Researchers then analyzed the data collected from 17,107 participants (321 Asian, 635 Black, 829 Hispanic, and 15,322 White) from April 2020 to January 2022. All participants had MCI or dementia and had a median age of 75.

Each participant underwent one amyloid PET scan. Researchers compared amyloid PET positivity proportions between matched ethnic and racial groups using the McNemar test and also used multivariable logistic regression to determine the odds of amyloid PET scan positivity.

“The proportion of amyloid positive PET scans was greater among White participants compared with Black and Asian participants,” the study found. “When racial and ethnic groups were matched by social and demographic factors, the proportion of amyloid positive PET scans was greater among White participants compared with Hispanic and Asian participants but not compared with Black participants.”

Researchers considered age, sex, and educational attainment, among other factors, when comparing 3,154 total participants (313 Asian to 313 White, 615 Black to 615 White, and 780 Hispanic to 780 White).

They found, among other results, that White participants were more likely to have a positive amyloid PET compared with Asian participants (p =.001) and Hispanic participants (p= .003) but not Black participants (p = .13).

The researchers said the results “have important implications for the diagnosis, treatment, and prevention of ADRD in groups that are at the highest risk of dementia.”

“Future research should include racially and ethnically diverse cohorts that reflect the burden of ADRD in the population at large,” they said. “The recently launched New IDEAS63 study is focused on addressing these gaps by using multipronged recruitment and community engagement strategies to evaluate the clinical utility of amyloid PET in a more diverse cohort of patients with MCI or dementia, with a specific focus on recruiting Black and Hispanic Medicare beneficiaries.”