Blacks more likely to have additional dementia-related changes in their brains
Alzheimer’s disease appears to develop differently in the brains of black patients and white patients, according to a new study. The study also finds that black people seem more likely to suffer different types of brain changes that also contribute to dementia.
Alzheimer’s disease is generally associated with a build-up of plaques and tangles inside the brain. This is considered “pure” Alzheimer’s. But the brains of people with dementia sometimes contain additional brain changes: infarcts, small areas of dead tissue caused by micro-strokes, and Lewy bodies, an abnormal protein build-up in the brain usually associated with Parkinson’s disease.
For the study, researchers looked at autopsies of black and white Alzheimer’s patients and discovered blacks were more likely than whites to experience a combination of dementia-related changes—the regular plaques and tangles, as well as infarcts and Lewy bodies. White Alzheimer’s patients were more likely to have the damage associated with “pure” Alzheimer’s dementia.
“We were surprised that the African Americans were much more likely to have a mixed picture,” said lead author Lisa Barnes, a professor of neurology and behavioral science at Rush University Medical Center in Chicago. “The underlying brain changes were different, which indicates that they probably had different risk factors.”
The study found that among 81 white patients who died, 42 percent displayed signs of typical Alzheimer’s disease only. About 51 percent of them had a mix of brain changes that included infarcts and Lewy bodies. Among 41 black patients who died, however, about 20 percent displayed only the usual Alzheimer’s plaques and tangles. More than 70 percent of the rest experienced infarcts and Lewy bodies on top of the usual Alzheimer’s brain changes. Blacks also had more frequent and severe blood vessel disease in their brains, such as hardening of the arteries.
This study could help explain why blacks in the United States are twice as likely to develop Alzheimer’s as people of European descent. Black folks are more likely than whites to suffer from heart disease, high blood pressure and type 2 diabetes, all of which increase the risk of infarct-causing strokes, Barnes said. The findings will be key to researchers seeking treatments for dementia, though further research is necessary to determine how early in life the dementia-related changes begin.
Dementia doesn’t refer to a specific disease, but a wide range of symptoms, including memory loss and communication problems significant enough to interfere with daily life, according to the Alzheimer’s Association.