African Americans Have a Higher Rate of Dementia Due to Strokes

Yale School of Medicine
Friday, 1 June 2001

African-Americans have a higher rate of dementia due to strokes and a lower prevalence of dementia stemming from Parkinson's Disease than do Caucasians, according to a study by Yale researchers published in the Journal of the American Geriatric Society.

Also, the genetic basis of Alzheimer's dementia appears to differ between African-Americans and Caucasians, said Sharon Inouye, associate professor of internal medicine and geriatrics at Yale School of Medicine and senior author of the study.

"The presence of a certain gene (apolipoprotein E allele, E-4 allele) is a potent risk factor for Alzheimer's Disease in Caucasians, but not for African-Americans," she said.

Dementia is an acquired persistent impairment of cognitive functioning and is a growing problem for the U.S. population. Currrently, 2.2 million Americans suffer from dementia. An estimated seven million to 10 million Americans will have severe dementia by the year 2040. Recent studies have estimated the total national costs for dementia at more than $67 billion annually.

Vascular dementia is associated with vascular disease and stroke and generally occurs in someone who has had multiple strokes. It can mimic the symptoms of Alzheimer's Disease, and in some cases, a person could be suffering from both forms of dementia.

Inouye also found that cultural and socio-economic biases in cognitive testing may lead to a misdiagnosis of dementia for African-Americans. "Some testing may assume the patient has certain cultural information or information gained through formal education," Inouye said. "For example, a patient might be asked to sequence pictures about an activity with which they are not familiar and may be misdiagnosed as being cognitively impaired."

She said physicians should be attuned to biases in testing and be more aware of factors contributing to vascular dementia when African-American patients come to them for dementia evaluations.

"One size fits all does not work in dementia research," Inouye said. "A certain genetic or causal model may not fit across all ethnicities and we might have to cast a broader point of view."

The other researchers on the study, which was supported in part by a grant from the National Institute on Aging, were Tanya Froehlich, M.D., principal investigator, and Sidney Bogardus, assistant professor of internal medicine and geriatrics and medical director of the Adler Geriatrics Assessment Center.

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