Alzheimer Diagnosis Tools Are Not Sufficient for Everyone
The way Alzheimer disease arises and develops is different depending on a person’s race due to a racial disparity in biomarkers for the disease, according to a new study.1
The researchers found that the level of the brain protein tau, the key biomarker used to identify Alzheimer disease, is lower in black individuals than in white individuals. In turn, individuals who are black might not meet the threshold to be diagnosed when the disease has already begun to develop in their brains.
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To study the connection between race and Alzheimer disease, the researchers enrolled 1255 participants (173 of whom were African Americans) in longitudinal studies at the Knight Alzheimer Disease Research Center at Washington University from April 22, 2016, to August 27, 2018.
Each participant completed at least 1 test for Alzheimer disease: a positron emission tomography (PET) scan to detect plaques of toxic amyloid protein in the brain, a magnetic resonance imaging (MRI) scan for signs of brain shrinkage and damage, and/or a spinal tap to measure levels of key Alzheimer’s proteins in the fluid that surrounds the brain and spinal cord.2
While the MRI and PET scans showed no significant differences between blacks and whites, the cerebrospinal fluid samples showed that the participants who were black had significantly lower levels of brain protein tau.
And while higher tau levels have been previously shown to be linked to brain damage, memory loss, and confusion, participants who were black—even those with lower tau levels—were still just as likely to be cognitively impaired than their white counterparts.
The difference in tau levels was even more pronounced among those with the high-risk gene apolipoprotein E ε4.
“We need to start looking into the possibility that the disease develops in distinct ways in various populations. People may be getting the same illness via different biological pathways,” said study co-author Dr John C Morris. “I think we’ll find we’ve been missing a lot by having such limited study populations in the past. We need to find out what else is going on, so we can develop better therapies that apply to everyone.”2
—Colleen Murphy
References:
1. Morris JC, Schindler SE, McCue LM, et al. Assessment of racial disparities in biomarkers for Alzheimer disease [published online January 7, 2019]. JAMA Neurol. doi:10.1001/jamaneurol.2018.4249.
2. Racial differences in Alzheimer’s disease unveiled [press release]. St. Louis, MO: Washington University in St. Louis; January 7, 2019. https://medicine.wustl.edu/news/racial-differences-in-alzheimers-disease-unveiled. Accessed January 7, 2019.