Brains of Black Americans age faster, study finds, with racial stressors a likely factor

The brains of Black adults in the U.S. age more quickly than those of white and Hispanic adults, showing features linked to Alzheimer’s disease and other dementias as early as mid-life, according to a new study.

The study, published Monday in JAMA Neurology, analyzed the MRI scans of nearly 1,500 participants from two racially and ethnically diverse cohorts. It found that Black adults in mid-life — on average, in their mid-50s — were more likely than white or Hispanic adults of the same age to have a higher prevalence of white matter lesions, markers of cerebrovascular disease that are associated with cognitive decline and Alzheimer’s disease.

Previous research has established stark racial disparities in Alzheimer’s disease, which affects more than 6 million Americans. Hispanic people are 1.5 times more likely to have the disease than white people, while Black people are twice as likely to have the disease compared to those who are white. The new study strengthens the case that vascular disease may be especially detrimental to brain health in Black populations, and may start to affect the brain far earlier in life than previously thought.

Adam Brickman, a professor of neuropsychology at Columbia University and the study’s senior author, said the research group wanted to understand when those racial and ethnic disparities began to manifest in the brain. But he did not expect to see brain aging start so early, and to do so only in the Black population. “It’s evidence that when we think about outcomes in late life, a lot of those changes are starting earlier in life,” he said. “Cognitive aging is a lifelong phenomenon, not just something that happens when you turn 65.”

The researchers do not think the differences can be chalked up to genetic factors. They hypothesize that early brain aging in Black participants was linked to weathering — the accumulation of racial stressors over time due to discrimination, poverty, residential segregation, pollution, and fears about personal safety. Weathering has been linked to a number of poorer health outcomes, including depression, migraines, hypertension, and higher infant and maternal mortality.

“The brains of Black participants in mid-life looked like the brains of older adults,” said Indira C. Turney, a cognitive neuroscientist  and associate research scientist at Columbia who was the paper’s lead author.

Given that Hispanic people also face structural inequities, the team was also surprised that early brain aging did not appear to the same extent in that cohort, which was made up largely of immigrants from the Dominican Republic and their children. This difference is something Turney plans to explore in future research.

The differences in the amount of brain aging between racial and ethnic groups were not as large among older adults. This may be because people with early brain aging in midlife are generally less healthy and may have shorter lifespans, Brickman said. Black adults who do survive into old age, he said, may be hardier and have healthier brains.

The study was applauded by many in Alzheimer’s research and advocacy because of its diverse pools of participants — the Washington Heights-Inwood Columbia Aging Project, known as WHICAP, which is made up primarily of people who are Black or Hispanic; and the Offspring Study of Racial and Ethnic Disparities in Alzheimer’s Disease, which includes children of WHICAP participants. This is a notable departure from typical Alzheimer’s studies, which have historically enrolled only a small percentage of Black and Hispanic people.

“It’s an exemplar,” said Andrea Gilmore-Bykovskyi, an Alzheimer’s researcher and associate professor of emergency medicine at the University of Wisconsin who was not involved with the study. “These are populations we need to be studying.”

To her, the study provides additional evidence that health care providers should take immediate steps to help patients prevent dementia by focusing on controlling high blood pressure and other aspects of vascular disease. “Cardiovascular disease is something that is largely modifiable,” she said. “This is something that can be done right now while progress toward disease-modifying drugs continues.”

Gilmore-Bykovskyi also said the study highlighted the need for the larger Alzheimer’s research and treatment community to pursue less popular areas of research, such as treating the vascular causes of dementia that may disproportionately affect non-white populations, with as much urgency as they do the search for new Alzheimer’s drugs.

“It’s unjust when we look at this cohort and see that modifiable risk factors affecting these populations that aren’t prioritized and aren’t pursued with the same funding and same vigor,” she said.

Stephanie Monroe, the executive director of African Americans Against Alzheimer’s, said the study emphasizes the importance of communicating the roles that conditions like vascular disease, diabetes, and hypertension play in dementia risk. “Heart health is brain health,” she said. “We need to talk about that.”

That prevention message is something Turney takes back to the community participants she works with who are eager to learn more about how to better care for their brains. She considers the research project to be a collaboration with participants, and says it’s important to listen to local communities about the directions that research takes. “As a scientist, you think you have a good research question, and the community will say, ‘I don’t care about that, why don’t you look at the air pollution in Harlem?’” she said.

Turney regularly takes part in the dementia education programs held in Washington Heights and Harlem to discuss nutrition, sleep, exercise, and other topics related to brain health. There are no PowerPoints on offer, just robust conversation. “These are not just data points,” Turney said. “These are people.”

This is part of a series of articles exploring racism in health and medicine that is funded by a grant from the Commonwealth Fund.

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