More than one third of American Indians/Alaska Natives over age 65 can expect to develop dementia before age 90, according to a new study published online by Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association.
The research project is the first to look at the incidence of Alzheimer’s, vascular dementia and non-specific dementia in AI/AN populations and Pacific Islanders.
The study was limited to older people, age 64+, who had not been diagnosed with dementia. It found that for the six racial/ethnic groups included in the study 38 percent of African Americans, 35 percent of American Indians/Alaskan Natives, 32 percent of Latinos, 25 percent of Pacific Islanders, 30 percent of Whites, and 28 percent of Asian Americans would develop dementia over the next 25 years of their lives.
“This study is an important first step. Our ultimate goal is to try to figure out targets for preventing dementia in all people and reducing the inequalities that we observed,” says one study author, Elizabeth Rose Mayeda, a postdoctoral fellow at University of California, San Francisco in the Department of Epidemiology and Biostatistics.
The Centers for Disease Control and Prevention defines dementia as “an umbrella term for a group of cognitive disorders typically characterized by memory impairment, as well as marked difficulty in the domains of language, motor activity, object recognition, and disturbance of executive function—the ability to plan, organize, and abstract.”
Two risk factors for dementia that cannot be changed are age and genetics, with age being by far the greatest risk factor. But heart-healthy habits, such as eating well, not smoking, keeping blood sugar, cholesterol and blood pressure in check and exercising may also help protect the brain from dementia, according to the Alzheimer’s Association.
Mayeda says education also appears to be an important protection against developing dementia. “Another thing that seems to be linked to dementia risk in addition to the heart-healthy factors is education. Access to education is something that has been shown to have a really profound effect on dementia risk, and not just how many years of schooling did you have, but did you have access to high-quality schooling?”
“So thinking on a population level, making sure that everyone has equal access to high quality education is one potential target for helping to reduce inequalities in dementia,” she says.
Continuing to lead an intellectually active life also has a positive effect. “Things that keep your brain active, things such as thinking, seem also to be things that protect your brain from dementia,” Mayeda says.
AI/AN populations suffer from high rates of cardiovascular disease, obesity and diabetes, which may be associated with their high incidence of dementia. “Cardiovascular risk factor does seem to be an important contributor to dementia risk and probably does contribute to these disparities that we observed in dementia [among different ethnic and racial groups],” says Mayeda.
“But,” she cautions, “More in-depth study [will be needed to] look at individual cardiovascular factors and see how much they contribute.”
The study, “Inequalities in dementia incidence between six racial and ethnic groups over 14 years,” is based on the electronic health records of more than 274,000 members of Kaiser Permanente, a northern California healthcare delivery system. The study population all had regular access to medical care from the same provider over the 14-year study period.
The incidence of dementia in AI/AN populations who do not have access to regular medical care may be even higher than the study found. “With any racial and ethnic group you can’t always translate the results [of one study] to everyone of that group because people live in different areas and are exposed to different social factors, such as having different access to health care. That probably does contribute to differences in health risk overall and dementia risk,” Mayeda says, noting that there is some research underway looking at dementia in American Indian communities on reservations.
Keith Fargo, Alzheimer's Association director of scientific programs & outreach, said, “Reducing disparities in Alzheimer’s for minority populations is identified as a priority by the National Plan to Address Alzheimer’s Disease. To achieve this goal, we need to understand why the risk for Alzheimer’s and dementia is different among ethnic and racial groups. This is an important area of research for the Alzheimer’s Association.”