Like many things in the United States, health and sickness are distributed unequally. One recent study quantified the "survival gap" between rich and poor: the wealthiest 1 percent of Americans live ten to 15 years longer than the poorest 1 percent. Being born in the wrong zip code, another revealed, could take 20 years off your life. And now, a new study shows that, for black people, moving out of segregated neighborhoods is linked to lower blood pressure.
The study, conducted by researchers at Northwestern University and published in JAMA Internal Medicine, examined data from more than 2,000 African Americans, drawn from neighborhoods in Chicago, Illinois; Birmingham, Alabama; Minneapolis, Minnesota; and Oakland, California. They were part of the Coronary Artery Risk Development in Young Adults (CARDIA) study, which followed participants for about 25 years; they were 18 to 30 years old when it began, and 43 to 55 when it concluded.
Over that time, researchers looked for associations between individual blood pressure and exposure to segregation. At the beginning of the study, 80 percent of participants lived in highly segregated neighborhoods—an eye-opening statistic in and of itself. Those who moved to less segregated neighborhoods over the course of the study saw a drop in blood pressure: specifically, their systolic blood pressure dropped 1 to 5 points. Those who'd moved to less segregated neighborhoods permanently saw the greatest drop, but even those who moved from their highly segregated neighborhoods and returned saw lasting improvements.
"In terms of impact, just 1 mm Hg of reduction of the systolic blood pressure at the population level could result in meaningful reductions in heart attacks, strokes, and heart failure," Kiarri Kershaw, lead author of the study and an assistant professor of preventive medicine at Northwestern University Feinberg School of Medicine, said in a statement.
Previous research has shown a relationship between residential segregation and hypertension, but this was the first study to show that association changing over time. Systolic blood pressure is the first number in a blood pressure reading; evidence from the CARDIA study showed it to be a better predictor of heart attacks and strokes in African Americans than diastolic, the second number.
"This study provides stronger, more direct evidence that segregation impacts blood pressure and harms the health of African-Americans," Kershaw said. "I believe it's related to the stress of living in these neighborhoods."
The study points to greater resources in less segregated neighborhoods, including better quality schools, access to public transportation, parks, health clinics, and supermarkets. Having those elements—the things that make a neighborhood a neighborhood—likely reduce stress and lower blood pressure. In other words, better neighborhoods mean healthier hearts.
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