Chronic Stress in African-Americans Linked to Hypertension

 

(UPDATED) Everybody experiences stress at some point, but when it persists over time, stress may increase the risk of developing hypertension, findings from a community-based cohort of African-Americans suggest.

In the Jackson Heart Study, participants who reported either moderate or high exposure to stress on annual assessments were more likely to develop hypertension by the next study visit, even after accounting for baseline stress levels and potential confounders like diet, smoking, and physical activity, according to researchers led by Tanya Spruill, PhD (New York University School of Medicine, New York, NY).

“None of those things actually explained away that relationship, so it really increased our confidence that there’s a true association: that stress really is increasing the risk of developing hypertension,” Spruill told TCTMD.

It’s important to emphasize that this study is unique in that it assessed perceived stress over time—as opposed to at a single point, she added. “Everybody is stressed from time to time, and that may not be dangerous, but it’s when it persists in a chronic way that we think it has health effects.”

In terms of practice, Spruill said, “one question that arises from this is whether screening for chronic stress in the clinical setting could be useful [to] identify people who might be at higher risk of developing hypertension or other chronic diseases.” The idea would be to find people who might benefit from stress management or reduction programs. Because this study is observational, however, it remains unknown whether reducing stress levels will stave off hypertension, and that needs to be tested in a clinical trial, Spruill noted.

Commenting for TCTMD, Clyde Yancy, MD (Northwestern Medicine, Chicago, IL), said in an email: “This paper supports the complex circumstances that are associated with the well-known and excess burden of hypertension in African-Americans. The authors suggest that African-Americans who perceive stress, broadly interpreted, may experience a higher likelihood of developing hypertension compared to those with a lower stress burden. Thus, in addition to ancestry, genetics, certain potential epigenetic considerations (ie, the interface between the environment and health), and the consequences of an adverse set of social determinants of health, we should also consider the negative consequences of stress. Though this relationship is intuitive, it does raise the possibility of different kinds of interventions reducing or mitigating stress that might be useful.”

Yancy had some caveats, however. “We don’t know the characteristics of what qualified as stress—eg, economic, employment status, family status—nor do we know the burden of stress, the time exposure to stress, and/or any overt efforts to manage stress,” he said. “Moreover, even with careful adjustment, other confounders may still account for the differences noted.”

Several messages can be taken away from this study, he said. “The burden of hypertension in African-Americans is compelling and has great consequence; the explanations for hypertension in African-Americans are both complex and protean and require ongoing work in multiple domains; and treatment of hypertension may well go beyond medical therapy to further include lifestyle, nonpharmacological approaches and, as suggested by these authors, even stress mitigation.”

The overarching message? “This paper reminds us once again to assiduously pursue the diagnosis of hypertension in all patients who self-assign as Black or African-American and then treat as per our extant guidelines,” Yancy said.

Jackson Heart Study

With this study, published online October 16, 2019, in the Journal of the American Heart Association, Spruill and her colleagues set out to better understand the relationship between stress and hypertension in African-Americans, who have both a heightened risk of high blood pressure and higher overall stress levels compared with their white counterparts. “Everybody has this idea that stress is bad for your health, increases the risk of hypertension and heart disease, but most of that research does not include large numbers of African-Americans,” Spruill said.

The Jackson Heart Study, a community-based investigation of the causes of CVD in African-Americans in the Jackson, MS, metropolitan area, provided an opportunity to address that deficit. A prior analysis of this cohort did not find an association between baseline stress levels and incident hypertension.

This new analysis, however, examined the impact of perceived stress at multiple points over time. It included 1,829 participants (mean age 49.3 years; 60% women) who did not have hypertension at baseline (2000 to 2004) and who completed multiple annual assessments that asked about how much stress they had experienced over the past year. Their answers were used to form three groups defined by perceived stress:

• Low: no ratings of “a lot” or “extreme” stress
• Moderate: one rating of “a lot” or “extreme” stress
• High: at least two ratings of “a lot” or “extreme” stress

Average blood pressure at baseline was 119/74 mm Hg. During a median follow-up of 7 years, nearly half of the participants (48.5%) developed hypertension. The rate of incident hypertension was 30.6% during times of low perceived stress, 34.6% during moderate-stress intervals, and 38.2% during high-stress intervals.

After adjustment for age, sex, and time, the risk of incident hypertension was elevated during exposure to moderate stress (risk ratio 1.19; 95% CI 1.04-1.37) and to high stress (risk ratio 1.37; 95% CI 1.20-1.57). Those findings were consistent in analyses that further adjusted for sociodemographic and hypertension risk factors, health behaviors, and baseline stress.

Although the stress-by-sex interaction was not statistically significant (P = 0.695), sex-stratified analyses showed that higher levels of stress were associated with incident hypertension in women, but not in men.

“Really what we think is that there are differences in the stress experience of women,” Spruill explained. “Women are exposed to different types of stressors. They might also perceive the same events or circumstances as more stressful than men. And they also, we think, react to stress differently in terms of things like emotional reactions, depression, and behavioral reactions. So it’s kind of this combination of factors of more stress and different reactions to stress that could explain that.”

Physiological, Behavioral Mechanisms at Play

Although this study wasn’t designed to explore mechanisms, Spruill said both physiological processes and behavioral pathways could be involved in explaining the relationship between chronic stress and hypertension.

Dawn Aycock, PhD, RN (Georgia State University, Atlanta), who was not involved in the study, agreed.

“We know that stress itself may contribute to hypertension, but we also know that when people are stressed they’re more likely to engage in unhealthy behaviors,” she said, such as eating unhealthier foods, consuming more calories, and smoking more.

Regardless of the reason why stress is associated with hypertension, Aycock said, “healthcare providers definitely need to ask individuals about their lifestyles and how much stress they may be experiencing. And what are their coping strategies, how do they deal with that stress? We know that we’re seeing more research that talks about the role of meditation, and also physical activity, as a stress reliever, so those may be things that we may recommend as far as helping individuals that are stressed with some coping strategies.”

Spruill said there have been some smaller studies evaluating stress reduction strategies and their impact on blood pressure, but indicated that additional research is needed.

“We’re very interested in mindfulness-based approaches, and there are some promising findings both in African-Americans and in the general population, so we’re hoping to conduct a larger trial testing something like that,” she said.

For Yancy, “we should for now remain straightforward in our approach to hypertension in all groups: diagnose, adopt lifestyle changes, and—where indicated—treat to goal.”