School of Medicine

Racial differences in Alzheimer’s disease unveiled

A new study at Washington University School of Medicine in St. Louis finds disparities between African-Americans and Caucasians in a key biomarker for Alzheimer’s disease – suggesting that tools to diagnose the disease in Caucasian populations may not work as well in African-Americans. (Getty Images)

Findings suggest possible race-linked variations on how disease arises, develops

From the WashU School of Medicine News

African-Americans may be twice as likely as Caucasian Americans to develop Alzheimer’s disease, but nobody knows why because studies investigating the underlying causes of illness have historically drawn from a nearly all-white pool of research participants. Consequently, little is known about how the neurodegenerative disease arises and progresses in people of non-Caucasian backgrounds.

Now, a new study from Washington University School of Medicine in St. Louis has identified racial disparities between African-Americans and Caucasians in the level of a key biomarker used to identify Alzheimer’s disease. The findings, published Jan.  7 in JAMA Neurology, suggest that tools to diagnose the illness may not as effectively apply to African-Americans. Specifically, the concern is that Alzheimer’s may be under-recognized in African-Americans because they typically have lower levels of the brain protein tau – meaning that people might not meet the threshold to be diagnosed when the disease already has begun to develop in their brains.

“If we only study Alzheimer’s in Caucasians, we’ll only learn about Alzheimer’s in Caucasians,” said John C. Morris, MD, the Harvey A. and Dorismae Hacker Friedman Distinguished Professor of Neurology. “If we want to understand all the ways the disease can develop in people, we need to include people from all groups. Without a complete understanding of the illness, we’re not going to be able to develop therapies that work for all people.”

Morris leads the university’s Charles F. and Joanne Knight Alzheimer’s Disease Research Center (ADRC). When he took over as principal investigator in 1997, Morris launched an initiative to address the lack of knowledge about the disease in people of color, and started by diversifying the center’s pool of study participants. At the time, only about 5 percent of people enrolled in memory and cognitive studies at the center were African-American, though they made up 18 percent of the population in the greater St. Louis area. With the guidance of an African-American advisory board led by civil rights activist Norman R. Seay, the ADRC steadily attracted a more representative participant group that allowed researchers to investigate the roots of racial differences in Alzheimer’s.

For this study, Morris and colleagues analyzed biological data from 1,215 people, of whom 14 percent, or 173, were African-American. The participants averaged 71 years of age. Two-thirds showed no signs of memory loss or confusion, and the remaining one-third had either very mild or mild Alzheimer’s dementia. All participants underwent at least one test for Alzheimer’s: a PET scan to detect plaques of toxic amyloid protein in the brain, an MRI scan for signs of brain shrinkage and damage, or a spinal tap to measure levels of key Alzheimer’s proteins in the fluid that surrounds the brain and spinal cord.

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