By Pat Anson, PNN Editor

Racial and ethnic bias is a fact of life that impacts almost every aspect of our society – and healthcare is no exception. Research has shown that African-Americans are more likely to be undertreated for pain compared to white Americans, and that blacks are less likely to be prescribed opioid pain medication than whites.

Part of that stems from a false belief that there are biological differences between blacks and whites that cause African-Americans to feel less pain.

New research published in the journal Nature Human Behaviour disputes that stereotype, suggesting that African-Americans experience more pain due to the lasting effects of discrimination and other stressful life experiences.

In a small study led by researchers at the University of Miami, 28 African-Americans, 30 Latinos and 30 whites were subjected to a series of painful heat tests on their forearms while undergoing MRI brain scans.

The African-Americans not only rated their pain more intense and unpleasant than the other two groups, but the MRI’s found that the parts of their brains that process pain signals became more active than their counterparts’ as the temperature of the heat probes increased.

“There's evidence that both the general public and clinicians believe that African Americans are less sensitive to pain than non-Hispanic whites; yet research, including our own, shows exactly the opposite." said lead author Elizabeth Losin, PhD, an assistant professor of psychology at the University of Miami.  "Minorities, particularly African Americans, actually report more pain."

Losin began her research eight years ago while at the University of Colorado, recruiting volunteers in the Denver area. In addition to the heat tests and MRI scans, all participants completed questionnaires about various aspects of their lives, including unfair social treatment, discrimination and their trust in doctors.

Using the MRI brain scans, Losin and her colleagues identified two areas of the brain, the ventral striatum and ventromedial prefrontal cortex, which responded to pain more strongly in African Americans than the other two groups. Prior research has found that these two brain regions also respond more to pain signals in chronic pain patients.

“Our findings suggest that the link between chronic pain and ethnic differences in pain sensitivity may lie in the chronic stress associated with discrimination. Discrimination has been consistently associated with chronic stress and other adverse health outcomes in AA (African Americans) and other minority groups,” Losin wrote.

“It is also plausible that the higher pain sensitivity we and others have observed in AA compared to WA (White Americans) participants may be related to previous negative experiences with medical care in particular, which are more common in AA compared to non-Hispanic WA populations.”

Previous studies have found that childhood trauma, domestic violence and other stressful life situations can also increase the likelihood of chronic pain – so this new research does not prove that discrimination alone contributes to the increased risk of pain. Nevertheless, it lays the groundwork for future studies on the relationship between pain and discrimination.

"These findings exemplify how neuroimaging is teaching us that there are multiple contributions to pain," said co-author Tor Wager, PhD, a professor of neuroscience at Dartmouth College. "We need to consider the broader psychological and cultural setting when we think about what is underlying pain and how to address it."

Losin is continuing her research by studying the relationship between patients' trust in their doctors and their experience with pain.

"It's a common misconception that any difference you see between groups of people must be an intrinsic difference, rooted in our biology. But the differences we found in this study were related to people's life experiences," she said. "It reaffirms our similarities and provides hope that racial and ethnic disparities in pain can be reduced."