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It goes like this. On her walk to work, a driver wolf-whistles at her. She sits in a meeting and gets interrupted when she speaks. She is also told, with a hint of surprise, that she’s pretty articulate. She vents on social media and is told by strangers to go back to the kitchen. She frowns at this—and is told to smile more.

These little hits of everyday discrimination are the daily realities for many women and people of color, says Danielle Beatty Moody, a psychology professor at the University of Maryland, Baltimore County. They are indignities so ostensibly subtle that people who don’t experience them firsthand often think nothing of them. But these slivers of “disdain, distance, and disrespect” add up, over days and years: “It’s like a thousand tiny cuts,” Beatty Moody says.

In a new study, she and her colleagues have found more evidence that these psychological cuts have real physiological consequences. As first reported by the journalist Emily Willingham, the team studied a racially diverse group of 2,180 American women and found that those who regularly experienced everyday discrimination ended up with higher blood pressure a decade later.

There’s already a large body of work that links everyday discrimination—racism, mainly—to a variety of mental and physical health problems, including disturbed sleep, unhealthy weight, and cardiovascular symptoms. But many of these studies are cross-sectional—that is, they compare people’s current experiences with their current health. They can’t say if the former caused the latter, because they are just momentary snapshots. To get stronger evidence, researchers need prospective studies, which track the health of volunteers over time.

One such study, known as SWAN, began in 1994 as an attempt to learn more about the health of middle-aged American women. Its 3,300 volunteers, who came from diverse racial groups and were from age 42 to 52, turned up for extensive annual checkups to monitor their health for more than two decades. As part of that, they also answered questions about their experiences of everyday discrimination.

Those questions were developed by David Williams of Harvard University to capture what he calls “the ways in which the dignity and the respect of people who society does not value is chipped away on a daily basis.” They ask how often people are insulted, threatened, or harassed in their day-to-day life; how often they’re perceived as dishonest, dumb, or scary; how often they get poorer service at restaurants and stores; and how often they’re treated with less courtesy and respect than others.

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By analyzing these data from the SWAN study, Beatty Moody and her team found that women who said they had experienced these slights “sometimes” or “often” had higher blood pressure than those who said they had experienced them more rarely. Specifically, after 10 years, the women’s systolic blood pressure was two units higher on average, and their diastolic blood pressure was one unit higher. That may seem small, but it makes a difference. One study that analyzed data from a million people concluded that if all middle-aged people reduced their systolic blood pressure by two units, deaths from heart disease and stroke would fall by 7 and 10 percent, respectively.

The only other prospective study that has considered discrimination and blood pressure found no link between the two, but it used only a small subset of Williams’s questions, and it tracked its volunteers only for four years. It may take longer for the consequences of discrimination to manifest, like a snowball gaining momentum as it rolls downhill.

Elizabeth Pascoe of the University of North Carolina at Asheville, who has also studied the link between discrimination and health, notes that it’s unclear whether Beatty Moody’s results would also apply to women of other age groups. Still, the study has many strengths. It used a scale that’s reliable and widely accepted, and its long-term data “increases support for a cause-and-effect relationship,” she says.

Beatty Moody’s team also found that women who experience more discrimination are more likely to put on weight, which in turn is linked to higher blood pressure. That makes sense, because routine discrimination is a chronic source of stress. “We often look for ways to manage stress, through self-soothing actions like eating food,” says Beatty Moody, “and our bodies are also doing it physiologically. Under stressful circumstances, we’re more likely to hold on to fat.”

It’s possible that overweight women are both more likely to face discrimination and have higher blood pressure, but the team tried to account for that. They reanalyzed their data after excluding any volunteers who thought that their physical appearance was the main reason for their negative experiences—and the results stayed the same. “When I first started this work, I really thought that the relationship between discrimination and blood pressure would stand on its own, independently of other traditional risk factors,” says Beatty Moody. “And that’s not how it works.”

That’s an important insight. When researchers look for connections between social experiences and health, they often treat traditional risk factors like body weight as “confounders”—that is, things that could also explain these connections, and should be adjusted for. That might be naive, because discrimination could influence those risk factors themselves.

“We certainly know that discrimination is bad for your health,” says Beatty Moody. “We’re beyond the point of that. We’re now trying to ask: For whom, how, and why?”

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