Experts explain the systemic, socioeconomic, and biological factors that play a role in dementia risk for Black Americans as compared to their white counterparts.
By 2030, experts estimate that more than 8 million Americans will be living with Alzheimer’s or other forms of dementia. Black Americans will make up a disproportionate amount of these cases as they are twice as likely to develop these diseases than whites.
But scientists aren’t sure exactly why that’s the case. Finding an explanation is especially important as new drugs like Aduhelm or Leqembi gain approval — as they could help answer whether these new treatments are safe and effective for Black Americans.
Here are some of the factors that experts believe contribute to the disproportionate dementia risk in Black Americans.
1. Systemic racism — and individual racism — increase dementia risk
Experts say that the long-lasting effects of systemically racist policies have led to an elevated risk for older Black Americans.
Residential segregation and redlining in the 1960s geographically isolated Black communities in areas that were exposed to higher levels of air pollution and fewer educational opportunities than white children. Each of these factors leads to an increased risk of developing dementia, and that translates to Black communities having some of the highest incidence of Alzheimer’s and dementia in the US.
“If you are African American and live in the United States, you may have greater exposure to things like structural racism, the historical practices of redlining, and other things,” Charles Windon, an assistant professor of neurology at the University of California San Francisco said in a recent Being Patient LiveTalk. “All the social determinants of health that can actually impact your risk of disease, and not only your risk of disease but actually the disease course in and of itself.”
On an individual level, exposure to racism and discrimination sets the brain into overdrive to help people cope, but it might lead to faster brain aging as a result.
“The more brain energy you use to suppress, control or manage your feelings, the more energy you take away from the rest of the body,” Emory University researcher Negar Fani and Harvard Researcher Nathaniel Harnett wrote in The Conversation. “In our research, we have found that this weathering process is evident in the gradual degradation of brain structure.”
2. Low socioeconomic status and poverty increase dementia risk
When it comes to dementia, the adage made famous by The Notorious B.I.G. — more money, more problems — does not hold true. Socioeconomic factors like living in lower-income neighborhoods, earning less money, or having parents who earned less money are risk factors for memory impairments and dementia.
Anthony Longoria, a researcher at the University of Texas Southwestern, found that poorer access to neighborhood resources was linked to lower cognitive scores in Black and Hispanic people but not white people. His study linked neighborhood income, violence, and lower access to healthcare and education to increased brain aging.
“This is important given that minority groups disproportionately experience economic adversity and neighborhood disadvantage, in addition to being more likely to be diagnosed with dementia and receive less timely care,” said Longoria.
3. More related health conditions and less access to healthcare
Black Americans are also more likely to have other chronic health conditions — like high cholesterol, high blood pressure, diabetes, or stroke — that also bump up their dementia risk when these conditions go untreated.
Black Americans have less access to quality medical care, and when they do go, they report being treated poorly. According to a survey by Pew Research, more than half of Black Americans have had negative experiences with healthcare providers in the past year — including having to speak up to ensure they got proper care or feeling like they were treated with less respect than other patients.
Almost two in three Black Americans, per the same survey, say their lack of access to high-quality medical care where they live is a major reason for the health disparities between them and white Americans.
4. Higher levels of food insecurity mean worse health
Eating a healthy diet that includes fresh fruit, vegetables, and whole grains can help promote healthy brain aging and reduce the risk of dementia and other cardiovascular diseases.
But compared to similar white communities, Black neighborhoods have fewer stores that offer fresh, healthy foods and have more convenience stores that sell ultra-processed junk food that can increase the risk of dementia.
“If you live in an area where you have a food desert, meaning you don’t have access to good nutrition,[…], you don’t have access to resources for physical activity; you oftentimes are at higher risk for things like comorbid, vascular conditions, hypertension, hyperlipidemia, and diabetes,” Windon said. “We know when you have these vascular conditions, it increases your risk of cerebrovascular disease as well, and cerebrovascular disease can cause cognitive impairment.”
5. Race-specific genetics and other biological factors impact Alzheimer’s risk
Some scientists are also looking at the underlying biology of Alzheimer’s and dementia for more clues.
Black Americans are more likely to carry the Alzheimer’s gene APOE4. While there is a strong association between the APOE4 gene and cognitive decline in whites, it does not appear to be as strong a driver of decline in Black Americans. Another gene called ABCA7 is linked to a higher risk of developing the disease, specifically in Black Americans, where it might even have more of an influence than APOE4.
It is also possible that the biology of the disease itself is a little bit different. Scientists are comparing the proteins, plaques, and pathology between Black and white brains post-mortem to tease out these differences.
Why don’t we know yet?
Renã A.S. Robinson, an associate professor at Vanderbilt University, explained that most research on Alzheimer’s disease has predominantly studied white Americans, making this a tricky question to answer.
“Even beginning to explain why disparities exist – much less reducing and eliminating them – is challenging, because basic science research studies are not including African Americans enough,” she wrote. “Inclusion of diverse groups in basic science research and clinical trials of Alzheimer’s disease is a critical first step to helping reduce and eliminate health disparities.”
Increasing the inclusion of diverse populations into clinical trials and other research studies of Alzheimer’s will help scientists begin to answer these questions.