On January 7, the science journal “JAMA Neurology” published a study conducted by researchers at the Washington University School of Medicine in St. Louis to determine the racial differences between African-American and Caucasian patients with Alzheimer’s. The results of the study indicate that some of the diagnostic techniques that doctors use to diagnose Alzheimer’s in Caucasians are less effective in diagnosing the disease in African-Americans. For example, African-Americans often have lower levels of a brain protein called tau than do Caucasians. High levels of the protein are linked to brain damage. Some African-Americans still showed dementia symptoms despite their lower tau levels.
The study’s lead author, Dr. John C. Morris, has been running the Charles F. and Joanne Knight Alzheimer’s Disease Research Center (ADRC) at the university since 1997. At that time, only five percent of study participants were African-American – even though African-Americans made up nearly a fifth of St. Louis’ population. With help from an advisory board composed of African-Americans, Morris implemented an initiative to attract more African-American participants.
From 2004 to 2015, Morris and his colleagues worked with 1255 participants, 173 of whom were African-American. The average age of the participants was 71. Roughly two-thirds of the participants had normal cognition, while the remaining third were in the early stages of Alzheimer’s.
Morris and his colleagues performed a variety of diagnostic tests on the volunteers. Such tests included magnetic resonance imaging (MRI) to detect brain damage and shrinking, positron emission tomography (PET) scan to detect toxic amyloid protein plaques and a spinal tap to measure levels of proteins associated with Alzheimer’s in the fluid around the spinal cord and brain.
The researchers then analyzed the results and found no significant differences in the MRI and PET scans between the two races. By contrast, the researchers found that African-Americans had lower levels of the protein tau but were just as likely to have Alzheimer’s as the Caucasian participants. Morris noted that the study’s results meant that doctors who used the spinal taps to diagnose Alzheimer’s risked missing signs of the disease in African-American patients.
The researchers also found that the gene variant, APOE4, which is a major cause of Alzheimer’s in Caucasians, had a much weaker effect on African-Americans. Caucasians with APOE4 had significantly higher tau levels than did African-Americans with APOE4. Morris speculated that the differences indicated that different biological pathways could lead to Alzheimer’s in different races or ethnic groups. He urged researchers to study groups like Hispanics, Native Americans, and Asian-Americans to identify any differences and develop more effective therapies.
