Doctors have long known that black people are more likely than white people to suffer from diseases such as high blood pressure. A study suggests that racial discrimination may be playing a role in a surprising way.
The study, which involved 150 African-Americans living in Tallahassee, Fla., found that knowing someone who had experienced racial discrimination was associated with genetic markers that may affect risk for high blood pressure.
The genetic markers "seem to interact with" being close to someone who has experienced racial discrimination, says Connie Mulligan, an anthropologist at the University of Florida who published the findings in the journal PLoS ONE on Wednesday.
The study also found an association with genetic markers previously shown to play a role in emotional problems, such as depression, anxiety and distress, Mulligan says. Mulligan doesn't know why discrimination experienced secondhand might have an effect when there was no association with experiencing discrimination firsthand. But she has some theories.
"It may be more distressful to hear about bad experiences happening to people close to you than experiencing them yourself," Mulligan says. "You might think, 'Well, I'm tough. I can handle it. I can handle whatever life throws at me. But don't you do anything to my little girl.' "
Mulligan says that other factors clearly play a role in causing disparities in health among minority groups. They may have difficulties getting access to quality health care because of economic reasons or a lack of health insurance.
Other researchers stressed that the research needs to be confirmed by follow-up studies. But they think the findings are intriguing.
"The report is very interesting," says Charles Rotimi, a senior investigator at the National Human Genome Research Institute. "It may begin to help us explain some of the disparities that we see."
But others questioned whether the study has found any link between genetic markers and an increased risk for high blood pressure.
"Simply having an association with DNA markers could lead you astray," says Troy Duster, a sociologist at the University of California, Berkeley. "The markers may have no connection to actual genetic function. It's a huge leap. We just don't know."
And even if the association is real, Duster questions the value of the findings.
"I don't see how this study helps us understand what anyone might do," Duster says. "If it's simply a matter of genetic associations with perceived stress, what's the implication? That you want to perceive less stress?"
But Mulligan argues that the findings are an important first step. "Bottom line: We have to understand what causes the problem before we have a chance of curing it," she wrote in an email.
"The study contributes to a growing body of research suggesting that unfair treatment and discrimination are important sources of stress, and that these stressors have real physical health implications," says Thomas McDade, an anthropologist at Northwestern University. "So if we really care about improving peoples' health, then one way to go is to try to reduce the burdens of stress and unfair treatment that people are experiencing," he says.
ARI SHAPIRO, HOST:
Maybe just knowing that someone else has experienced racial discrimination is bad for your health. Provocative new research raises that possibility. NPR health correspondent Rob Stein explains.
ROB STEIN, BYLINE: Doctors have known for a long time that African-Americans are more likely than whites to suffer from many diseases, including high blood pressure. Connie Mulligan of the University of Florida wanted to know how racial discrimination may be playing a role in that.
CONNIE MULLIGAN: Discrimination has been studied a lot for its effect on mental health. It's been less studied for its effect on physical health, something like blood pressure.
STEIN: So Mulligan and her colleagues studied more than 150 African-Americans living in Tallahassee. They analyzed their genes, measured their blood pressure and quizzed them about their experiences with racial discrimination.
MULLIGAN: Things got really interesting when we found that many, many people - well over half the people - would talk about experiences of discrimination that they themselves had not had but that people close to them had - their significant other, their parents, their kids, their friends, coworkers, that sort of thing.
STEIN: So the researchers looked at whether that kind of secondhand discrimination had any relationship to their blood pressure and to their genes.
MULLIGAN: What we found is a whole new class of genes that seem to interact with when people close to you are exposed to unfair treatment. That puts the individual at higher risk for high blood pressure.
STEIN: Genes that had already been shown to possibly play a role in emotional problems such as depression, anxiety and stress. Now, Mulligan doesn't know why secondhand discrimination would do this to people carrying these genes, but she has some theories.
MULLIGAN: It may be more distressful to hear about bad experiences happening to people close to you than experiencing them yourself. You might think, well, I'm tough; I can handle it, you know? I can handle whatever life throws at me. But you know, don't you do anything to my little girl.
STEIN: Mulligan isn't saying that other factors aren't important. Blacks have a harder time just getting access to good medical care than whites, for example. But Mulligan says the new findings suggest that there's more than that going on.
MULLIGAN: What I think is really exciting about our study is this idea of interactions between genetics and something like discrimination. That opens a whole new window in what might be causing racial disparities in disease.
STEIN: Now, some researchers are skeptical that Mulligan has made the case that these newly identified genes are really interacting with secondhand discrimination to affect blood pressure. And even if it turns out that that's true, Troy Duster of the University of California, Berkeley, questions how helpful that is.
TROY DUSTER: I don't see how this study helps us understand what anyone might do. If it's simply, quote, "a matter of genetic associations with perceived stress," what's the implication - that you want to perceive less stress (laughter)?
STEIN: But others argue the research provides an important new way to think about discrimination and health. Thomas McDade is an anthropologist at Northwestern.
THOMAS MCDADE: The study contributes to a growing body of research suggesting that unfair treatment and discrimination are important sources of stress and that these stressors have real physical health implications. So if we care about improving people's health, then one way to go is to try to reduce the burdens of stress and unfair treatment.
STEIN: But it's clear that a lot more research is needed to better understand the relationship between racial discrimination, genetics and health. Rob Stein, NPR News. Transcript provided by NPR, Copyright NPR.