For black adults, moving out of a racially segregated neighborhood is linked to a drop in blood pressure, according to a new study. The finding adds to growing evidence of an association between a lack of resources in many predominately black neighborhoods and adverse health conditions among their residents, such as diabetes and obesity.
Systolic blood pressure — the pressure in blood vessels when the heart beats — of black adults who left their highly segregated communities decreased just over 1 millimeter of mercury on average, researchers report online May 15 in JAMA Internal Medicine. This decline, though small, could reduce the overall incidence of heart failure and coronary heart disease.
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“It’s the social conditions, not the segregation itself, that’s driving the relationship between segregation and blood pressure,” says Thomas LaVeist, a medical sociologist at George Washington University in Washington, D.C., who was not involved with the study. “Maybe hypertension is not so much a matter of being genetically predisposed.” That’s important, LaVeist adds, because it means that racial health disparity “can be fixed. It’s not necessarily contained in our DNA; it’s contained in the social DNA.”
Racial segregation can impact a neighborhood’s school quality, employment opportunities or even whether there is a full-service grocery store nearby. Social policies that improve residents’ access to education, employment and fresh foods can “have spillover effects in health,” says Kiarri Kershaw, an epidemiologist at Northwestern University Feinberg School of Medicine in Chicago.
Kershaw and colleagues examined data from a study of how cardiovascular disease progresses in healthy adults, aged 18 to 30, who were recruited from four locations: Chicago, Minneapolis, Oakland, Calif., and Birmingham, Ala. The researchers specifically looked at blood pressure readings for 2,280 black participants, recorded at six points over 25 years, and noted their addresses at the time of each reading. A neighborhood’s designation of high, medium or low racial segregation was based on the percentage of black residents in the neighborhood compared with the larger metropolitan area or county, Kershaw says.
At the start of the study in the mid-1980s, 1,861 participants were living in highly segregated neighborhoods. A temporary move to a less segregated neighborhood, the researchers found, was associated with a 1 millimeter of mercury drop in blood pressure on average.
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If the change of address was permanent — as it was for 243 participants — the impact was greater. On average, blood pressure dropped close to 6 millimeters of mercury for those who moved to low-segregation neighborhoods, and nearly 4 millimeters for a move to a medium-segregation neighborhood.
A 2015 study in the Journal of the American Heart Association estimates that a decrease in systolic blood pressure of 1 millimeter of mercury could result in several thousand fewer cases of heart failure, stroke and coronary heart disease annually in the U.S. population of black adults aged 45 to 64, Kershaw says.
Along with other research on racial segregation and health, the findings suggest that policies that improve housing conditions, educational resources and employment opportunities “will have implications for the health of individuals,” LaVeist says. “Social policy is health policy.”