Black people in the US have worse chronic pain than white people due in part to gene expression.
Chronic stress has previously been linked to racial discrimination, and can lead to changes in gene expression. at the University of Alabama at Birmingham and his colleagues collected blood samples from 98 people 鈥� half were Black and half were non-Hispanic white, and they had an average age of 45. Half the group had chronic lower back pain, while the rest were pain-free.
Everyone with chronic pain was asked to report how bad their pain was and how much it affected their daily lives. Black participants had higher scores on both counts than their white counterparts.
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The researchers wanted to see if they could find biological markers that would explain this. They analysed the participants鈥� blood samples using genetic sequencing that identifies which sections of DNA have small molecules called methyl groups attached. This methylation can happen for a variety of reasons, including ageing and chronic stress.
Methyl groups may change the activity of DNA, but they don鈥檛 change its sequence. Previous studies have shown that methylation may be linked to poorer health outcomes.
In this study, there were 110 signalling pathways with significantly more methylated genes in Black people with chronic pain than in Black participants who were pain-free. These pathways have been tied to chronic pain. There were 31 pathways with more methylated genes in white people with chronic pain than in white participants without such pain.
鈥淭he study begins to validate the fact that chronic stress experienced by Black people is causing actual harm,鈥� says Aroke. The team didn鈥檛 quantify experiences of racism by the participants, but the findings imply that institutional racism may play a role, he says.
DNA methylation is reversible, so聽interventions targeting racism may also reduce ethnic disparities in聽chronic pain, says Aroke.
at Michigan State University says the findings are interesting. 鈥淭his study may be the first step to us understanding the racial disparities in the risk of chronic pain,鈥� he says.
Neurobiology of Pain
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