Scientists have found a biological clue that could help explain why African Americans appear to be more vulnerable than white Americans to Alzheimer’s disease.
A study of 1,255 people, both black and white, found that cerebrospinal fluid from African Americans tended to contain lower levels of a substance associated with Alzheimer’s, researchers report Monday in the journal JAMA Neurology.
A colorized image of a brain cell from an Alzheimer’s patient shows a neurofibrillary tangle (red) inside the cytoplasm (yellow) of the cell. The tangles consist primarily of a protein called tau.
Yet these low levels did not seem to protect black participants from the disease.
The finding “implies that the biological mechanisms underlying Alzheimer’s disease may be very different in [different] racial groups,” says Dr. John Morris, an author of the paper and director of the Knight Alzheimer’s Disease Research Center at Washington University in St. Louis.
And if Alzheimer’s works differently in African Americans, that difference could make them more vulnerable to the disease, Morris says.
The study has limitations, though, says Lisa Barnes, a cognitive neuropsychologist at the Rush Alzheimer’s Disease Center in Chicago, who wrote an accompanying editorial.
For example, it could not fully account for the effects of some other known Alzheimer’s risk factors — including hypertension, diabetes and obesity — or some suspected risk factors, including stress and poverty. Also, the study included just 173 African Americans and was able to obtain spinal fluid samples from only half of them.