Gene Doubles Risk of Late-Onset Alzheimer’s in Blacks

Black people with a certain genetic variant may face a doubled risk of late-developing Alzheimer’s disease, a study found.

The gene, dubbed ABCA7, is not as important for white patients, according to the study published today in the Journal of the American Medical Association. The DNA’s involvement in processing cholesterol and lipids, though, is consistent with a higher prevalence in blacks of heart disease and strokes, the researchers wrote.

The study included almost 6,000 black people ages 60 or older who were mostly volunteers from 18 Alzheimer’s disease centers funded by the U.S. National Institutes of Health. The scope of the trial makes it unique because blacks are only 10 percent of the elderly population, said Richard Mayeux, the study author.

“This is a big part of the population that’s really understudied,” said Mayeux, who is chairman of neurology at Columbia University Medical Center in New York. “Most of the gene discoveries have been in white populations, and if the goal is to identify potential treatments, then to not look at an African American population is a big mistake.”

More than 5 million Americans have Alzheimer’s, which is the most-common type of dementia, according to the Alzheimer’s Association. Global dementia cases are expected to double within 20 years to as many as 65.7 million people, the Geneva-based World Health Organization has said.

The research, funded by the National Institute on Aging, found that ABCA7 boosted the risk of Alzheimer’s about 1.8-fold in blacks compared with about 1.1-fold in those of European descent. About a third of those studied had been diagnosed with Alzheimer’s and two-thirds were cognitively normal, according to the study.

Late-onset Alzheimer’s is more common among blacks than in whites living in the same community. This finding may help explain why, Mayeux said in a telephone interview.

“We found a gene that was just under the radar screen in most studies of whites,” he said. “It’s a major player in this group.”

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