Everyday experiences of racism can impact your brain-gut microbiome, new study shows
It's proven that experiencing systematic racism negatively affects one's mental health.
But it can also lead to diseases associated with inflammation, such as rheumatoid arthritis and autoimmune inflammatory disease, according to a new study published in Biological Psychiatry.
It's one of the few studies that considers how environment, not just genetics or hereditary traits, affect biology, says Aparna Gupta an associate professor at University of California, Los Angeles who co-authored the study. Gupta is also the co-director of the UCLA Microbiome Center and her research focuses on how the brain-gut microbiome system is influenced by adversity.
"How we treat people and how we are interacted with has huge impacts on how it affects your biology," she says. "Those interpersonal relationships can have huge impacts all the way down to your microbiome."
Racial discrimination led to 'more inflammation in the body'
The study included 154 adults who self-identified as Asian American, Black, Hispanic, or White. All reported experiencing discrimination.
White participants didn't feel like their discrimination was race-based, but had more to do with their gender or age. Black, Hispanic, and Asian American participants all felt the discrimination they experienced was race-based.
To assess their physical health, researchers collected MRI scans to view brain connectivity, blood tests to measure inflammatory markers, and fecal samples to identify the microbial population and metabolites.
Black and Hispanic participants had increased levels of a gut bacteria which is associated with rheumatoid arthritis and autoimmune inflammatory disease.
In Asian Americans, researchers saw an uptick of metabolites associated with cholesterol, which could be evidence of increased consumption of fatty foods.
White participants did not have inflammation.
"Discrimination based on race or ethnicity had a lot to do with more inflammation in the body which led to changes in the microbiome which led to inflammatory response," says Tien S. Dong, an assistant professor at UCLA who also co-authored the study. Dong' s research focuses on the gut microbiome and liver disease.
"This kind of chronic inflammatory response can lead to negative health outcomes, we've seen in prior research."
'That stressor or injury was still there'
Mental effects also varied across race, but all races had an increase in emotional arousal or parts of the brain associated with fight or flight.
White participants felt increased anxiety.
Asian Americans had increased connectivity in the sensorimotor network, which indicates disrupted sensory functions and is often observed in "patients with major depressive disorders," the study reads.
Black and Hispanic participants, specifically, experienced increased connectivity in the part of the brain associated with self-reflection. Hispanics also experienced more connectivity in the part of the brain associated with hypervigilance.
Being able to calmly recall painful experiences, Dong and Gupta agreed, might make it appear like those experiencing racism are doing fine. But the study shows that this discomfort might be revealing itself in another way.
"You've experienced discrimination for a long time and to be able to function you had to find ways to cope mentally either through resilience or self-reflectiveness," Dong says. "But that stressor or injury was still there. Instead of manifesting itself through anxiety and depression like their white Caucasian counterparts they internalize it biologically."
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