January 8, 2019
Research on Alzheimer’s has mainly focused on Caucasians. New findings, however, suggest the disease process that leads to dementia may differ in African–Americans. According to a study published Monday in JAMA Neurology, the brains of African–Americans diagnosed with Alzheimer’s have less buildup of a protein called tau—one of the two hallmark proteins that characterize the disease.
It is not clear why African–Americans would have less tau while still suffering from Alzheimer’s, says neurologist John Morris, who led the research. But the finding is significant because it means the medical community needs to exercise caution when defining Alzheimer’s by measures of tau buildup alone. The study also suggests race might affect other aspects of the disease’s pathology, says Morris, who directs the Knight Alzheimer Disease Research Center at Washington University in Saint Louis. “The study of Alzheimer’s disease, which really began formally in the United States in the mid-1980s, has largely been of white people,” he notes. “The U.S. in general and the older adult portion of the U.S. population is increasingly diverse, so we really do need to study all populations to try to understand the disease and its forms.”
For the moment, the differences detected in the disease’s pathology will not change existing treatment protocols, which do not yet look at certain aberrant proteins to make a diagnosis. Physicians today diagnose Alzheimer’s largely based on a patient’s neuropsychological characteristics. But once researchers have developed a more practical way to measure levels of key proteins involved in the disease, such differences could be crucial for accurate diagnoses, Morris says. Brain scans can detect tau as well as amyloid beta—another protein that builds up in the brains of Alzheimer’s sufferers—but the scans are expensive and not widely available.
The study found no racial difference in amyloid levels. African–American study participants, though, had a much lower concentration of tangled clumps of the tau protein, whether or not they had dementia. The research looked at 1,255 people – some with Alzheimer’s, some cognitively normal – including 173 African–Americans.