Stress from interpersonal conflict may spur high blood pressure

In a recently released study, psychologists Rodlescia Sneed and Sheldon Cohen of Carnegie Mellon University found that negative social interactions can increase the risk of hypertension in older adults. But their findings weren’t true across the board. Women, it turns out, take conflict to heart much more than men do.

For decades, scientists have known that the wider your social circle, the healthier you are likely to be. As far back as 1987, researchers found that, in Alameda County, Calif., residents with more close friends and family members had higher chances of living longer.

“It is very clear that people who are lonely and who feel socially isolated are at greater risk of heart disease,” said Karen Matthews, professor of psychiatry and epidemiology at the University of Pittsburgh.

For more than 10 years, Matthews has been studying the link between social interactions and cardiovascular health. She has equipped her subjects with cuffs that measure blood pressure once every 30 or 45 minutes throughout their day. When the cuff inflates, participants stop and write down their recent activity: where they are, who they have been with, and what they have been doing.

Those who have had social contact in the last 10 minutes generally have lower blood pressure, Matthews said.

Cohen has himself spent 30 years looking at how psychological factors influence our susceptibility to colds. In these studies, participants were asked about their social lives before researchers dropped virus-infected liquid into their nostrils. Then, the participants were quarantined and monitored for five to six days. Cohen discovered that the more social roles one played — such as being a parent, spouse, friend, volunteer or member of a religious group — the stronger one’s immunity to colds.

But social contact is a double-edged sword. Almost all previous research was about how many social contacts or roles you had, and not about their quality, said Cohen and Sneed. An even tinier fraction of scholarship existed about the possible negative impact of social interactions. And of that, almost all of it looked at the effects on mental health.

The two psychologists were interested especially in the consequences of those social situations we find unpleasant. They wanted to know how criticism, let-downs and nagging could affect your physical health.

To find out, they looked at data from the Health and Retirement Study, a long-term survey conducted by the University of Michigan. More than 6,000 people provided information on both their social interactions and hypertension in 2006 and 2010, but Sneed and Cohen excluded all who had been previously diagnosed with hypertension. They wanted to see if the frequency and intensity of unpleasant interactions reported in 2006 were linked to the onset of hypertension among the 1,502 participants who did not already have high blood pressure.

What they found was striking. If, on average, you rated your negative interactions at 2 out of 4, you were 38 percent more likely to develop hypertension in the next four years than if you had rated those interactions at 1. And for each higher rating of unpleasant interaction, participants were 38 percent more likely to get high blood pressure.

Yet these findings were only true of women between the ages of 51 and 64. Sneed and Cohen suggested that women put more stock in their social lives than men do, and that those 65 or over might have figured out how to better mitigate the damage of toxic relationships, but the gender and age differences are still open to interpretation.

From a physician’s perspective, Sneed and Cohen’s study is well put together, but the idea will require more research before its effects can be seen in the clinic, said Matthew Muldoon, an internal medicine specialist at UPMC.

“It’s one thing to say that dietary salt raises blood pressure,” Dr. Muldoon said. “It’s less obvious how being in a stressful relationship can raise blood pressure.”

Yet many of his hypertension patients attribute the condition to stress, and he feels this study is a step in the right direction.

Lowering stress has long been advised to help people avoid developing high blood pressure. Other tips include doing more exercise, reducing salt intake, and limiting alcohol consumption.

For Sneed, the disease’s prevalence makes it an especially important subject for psychological research. At least 70 percent of all Americans have high blood pressure by the age of 65. It is one of the leading risk factors for heart disease, the single biggest killer in the United States.

The exact mechanism that allows social interactions to affect our cardiovascular system remains unknown. But as Sneed has observed, “Social stress is the most commonly reported kind of stress.”