It’s been well documented that African-Americans are at higher risk of developing high blood pressure (hypertension) than other racial and ethnic groups in the United States. Here in Minnesota, for example, 30 percent of African-Americans have high blood pressure compared to 24 percent of whites, according to the Minnesota Department of Health.
Because behavior factors, such as physical activity, obesity and smoking, do not fully explain this increased risk, researchers have proposed another possible cause: the stress of discrimination.
A new study, published Wednesday in the journal Hypertension, adds credence to that explanation. It found that African-Americans who had experienced the stress of lifetime discrimination were up to 50 percent more likely to develop high blood pressure than those who reported lower levels of discrimination.
The findings add to the growing body of research that has pointed to discrimination as a driving factor behind racial health disparities in the United States. Those disparities are considerable. African-Americans are not only more likely than other racial groups to develop high blood pressure, but also such chronic diseases as type 2 diabetes, heart disease and stroke. In addition, they have the highest death rate of any racial and ethnic group in the U.S. for most types of cancers.
The current coronavirus pandemic has accentuated racial health disparities. The overall death rate from COVID-19 has been 2.4 times higher for African-Americans than it has been for white Americans.
Previous studies have examined the contribution of discrimination to racial disparities in high blood pressure, but with mixed findings. Those studies have tended to be small, however, and were limited in how they assessed discrimination. The current study used a large sample of African-Americans and relied on more detailed measures of discrimination.
Two types of discrimination
For the study, researchers used data on 1,845 African-American participants, aged 21 to 85, in the Jackson Heart Study, an ongoing project that has been investigating the risk factors associated with cardiovascular disease among African-American men and women in the Jackson, Mississippi, area. This particular group of participants had first joined the Jackson Heart Study between 2000-2004, and at that time none of them had high blood pressure. During the next decade or so, they completed two additional study visits: one in 2005-2008 and another in 2009-2013. By the end of the second visit, about half of the participants — 954 — had been diagnosed with high blood pressure.
When they entered the Jackson Heart Study, the participants had answered detailed questions designed to measure two categories of discrimination: “everyday” (daily hassles and insults, such as receiving poorer service at a restaurant or being followed while in a store) and “lifetime” (major episodes, such as an unfair rejection for a job promotion or being prevented from moving into a neighborhood). The authors of the current study looked for a link between those forms of discrimination and the likelihood of developing high blood pressure.
They found one. People who reported medium levels of lifetime discrimination were 49 percent more likely to have high blood pressure than those who reported low levels, even after taking into account well-established risk factors for high blood pressure, such as age, body mass index, physical activity and income level.
Interestingly, there was no dose-responsive relationship reflected in the findings. People who reported high levels of lifetime discrimination were 34 percent more likely to have high blood pressure than those who reported low levels.
No association was found between everyday discrimination and an increased risk of high blood pressure.
Limitations and implications
This was an observational study. As a result, it demonstrates only an association, not a direct cause-and-effect relationship, between lifetime racial discrimination and high blood pressure. In addition, the participants were asked about their experiences of discrimination at a single point in their lives. The stress associated with those experiences may have changed over time — a factor that could have affected the findings.
Still, “our results suggest that discrimination is a chronic stressor that may increase the risk of hypertension,” the study’s authors write.
“Previous studies have shown that discrimination affects African American’s health; however this research is one of the first large, community-based studies to suggest an association between discrimination over a lifetime and the development of hypertension among a large sample of African American men and women,” said Allan Forde, the study’s lead author and a postdoctoral researcher at Drexel University, in a released statement.
“The study has important implications for patient care and population health,” he explains. “Traditional risk factors, such as diet and physical activity, have been strongly correlated with hypertension, yet important psychosocial factors like discrimination, which also have the potential to negatively impact health, are rarely considered when evaluating the risk for hypertension among African Americans in health care settings.”
“Addressing these factors is critical to reducing rates of chronic disease,” he adds.
FMI: You’ll find the study on Hypertension’s website. Hypertension is published by the American Heart Association, which offers tips on its website for how you can keep your blood pressure under control.