While certain minority groups are more likely to be diagnosed with dementia than their white counterparts, they may also be less likely to be eligible for new disease-slowing treatments, a new study finds.
Cognitive, or mental, impairment in Black, Hispanic and Asian patients is more likely to be caused by forms of dementia unrelated to the amyloid plaques now being treated with anti-amyloid monoclonal antibodies. These drugs are offering fresh hope to those who can receive the treatment, the researchers said.
“Public health efforts to better diagnose and treat non-amyloid variants of dementia will be critical if we are to reduce disparities in dementia care,” said study co-author Dr. Gil Rabinovici, of the University of California, San Francisco, Memory and Aging Center.
For this study, the researchers examined the differences in amyloid deposition among 17,000 patients who had dementia or its frequent precursor, mild cognitive impairment (MCI).
Study participants were Asian, Black, Hispanic and white Medicare beneficiaries enrolled in the Imaging Dementia — Evidence for Amyloid Scanning (IDEAS) study.
About 61% of participants had MCI, in which someone experiences thinking and memory issues but can live independently. About 31% had dementia, in which they were impaired to the point they required assistance for daily functions.
The researchers matched 313 white people with 313 Asian people according to age, sex, education, living arrangement, level of impairment, history of diabetes and high blood pressure, as well as family history of dementia.
The investigators found that 45% of the Asian participants tested positive for amyloid plaques. That compared to 58% of the white participants.
The team also matched 615 Black people with 615 white individuals. They found 54% of Black people had amyloid plaques compared to 58% of white people.
When researchers matched 780 Hispanic people with 780 white people, they found that 55% of Hispanic people had plaques compared to 62% of white people.
In those who specifically had MCI, the team found that percentages of positivity declined to 36% for Asians versus 53% for whites; 42% for Black people versus 49% for white people; and 46% for Hispanic people versus 53% for white people.
“A higher proportion of Black and Hispanic patients presented to specialists at the dementia stage, rather than at the MCI stage, but the benefit of these new therapies is expected to be greater in earlier stages of the disease,” Rabinovici noted.
“Lack of access to diagnosis and care at an early stage of disease could further exacerbate disparities in dementia care and outcome,” he added.
The new anti-amyloid monoclonal antibodies are the first class of drugs designed to address the underlying biology of Alzheimer's disease, rather than its symptoms, according to the study authors.
The U.S. Food and Drug Administration approved the premier drug, Aduhelm, in 2021. Last month, a phase 3 trial of a second drug, lecanemab, found it appeared to slow the rate of cognitive decline. Two other therapies could follow within the next several months.
The lower rates of amyloid positivity among Black and Hispanic patients could reflect differences in the cause of cognitive impairment, such as higher rates of high blood pressure and diabetes, said study co-author Dr. Consuelo Wilkins, a geriatrician at Vanderbilt University Medical Center, in Nashville, Tenn.
Previous research also found that, among those studied, Asian Americans may have the lowest incidence of dementia. This is “difficult to interpret due to different social factors and co-existing health conditions among Asian subgroups,” Wilkins said.
Rabinovici said he would favor regulatory requirements to ensure study participants are racially and ethnically representative of patients with the disease.
“We can draw inspiration from COVID-19 vaccine trials that demonstrated this can be done when utilizing state-of-the-art inclusive research practices and allocating adequate resources,” Rabinovici said in a university news release.
The researchers found that other factors also increased odds of amyloid positivity, including older age, female sex and higher education.
The report was published online Oct. 3 in JAMA Neurology.
The U.S. National Institute on Aging has more on Alzheimer's disease and related dementias.
SOURCE: University of California, San Francisco, news release, Oct. 3, 2022