Racial discrimination in Black Americans is associated with an increased risk of developing Alzheimer’s disease (AD) in later life, new findings showed.
Researchers found that Black Americans who experience racism in their 40s and 50s are more likely to have increased serum levels of AD biomarkers p-tau181 and neurofilament light (NfL) more than a decade later.
“We know that Black Americans are at an elevated risk of Alzheimer’s disease and other dementias compared to non-Hispanic White Americans, but we don’t fully understand all the factors that contribute to this disproportionate risk,” Michelle Mielke, PhD, co-author and professor of epidemiology and prevention at Wake Forest University School of Medicine, Winston-Salem, North Carolina, said in a press release.
Recent data show AD is twice as prevalent in Black Americans as in Whites, at 18.6% and 10%, respectively. Dr. Mielke said this level of disparity cannot be attributed solely to genetic differences, and evidence suggests that racism and its related stress may play a role.
The findings were published online in Alzheimer’s and Dementia.
AD Biomarker Testing
To further explore a possible link between exposure to racism and AD risk, investigators analyzed data from the Family and Community Health Study, a multisite, longitudinal investigation that included more than 800 families in the United States.
Blood samples and information on racial discrimination were collected from 255 middle-aged Black Americans between 2002 and 2005.
Blood samples were tested for serum phosphorylated tau181 (p-Tau181), a marker of AD pathology; NfL, a nonspecific marker of neurodegeneration; and glial fibrillary acidic protein (GFAP), a marker of brain inflammation.
Participants answered questions about racial discrimination, which included whether they have been subjected to disrespectful treatment including racial slurs, harassment from law enforcement, or if they had ever been excluded from social activities because of their race.
The sample included 212 females and 43 males with a mean age of 46. Most participants (70%) lived in urban areas.
Stress-Related?
Investigators found no correlation between racial discrimination and increased levels of AD blood biomarkers in 2008 when participants were a mean age of 46 years. However, 11 years later, when participants were roughly 57 years old, investigators found experiencing racism in middle age was significantly correlated with higher levels of both p-Tau181 (r = 0.158; P ≤ .012) and NfL (r = 0.143; P ≤ .023). There was no significant association between reported discrimination and GFAP.
“These findings support the hypothesis that unique life stressors encountered by Black Americans in midlife become biologically embedded and contribute to AD pathology and neurodegeneration later in life,” the authors wrote.
Investigators speculated based on previous research that the stress related to discrimination may be associated with reductions in hippocampal and prefrontal cortex volumes and neurodegeneration in general.
Dr. Mielke also said it’s clear that future studies should focus on racism experienced by Black Americans to further understand their risk for dementia.
“This research can help inform policies and interventions to reduce racial disparities and reduce dementia risk,” she said.
Study limitations include the absence of amyloid biomarkers. Investigators noted that participants had non-detectable levels of amyloid, likely due to the use of serum vs cerebrospinal fluid.
The study was funded by the National Institute on Aging and the National Heart, Lung, and Blood Institute. Mielke reported serving on scientific advisory boards and/or having consulted for Acadia, Biogen, Eisai, LabCorp, Lilly, Merck, PeerView Institute, Roche, Siemens Healthineers, and Sunbird Bio.
A version of this article appeared on Medscape.com.