Hardening of the coronary arteries is more likely in wives when they and their husbands express hostility during marital disagreements, and more common in husbands when either they or their wives act in a controlling manner.
Those are key findings of a study of 150 healthy, older, married couples - mostly in their 60s - conducted by Professor Tim Smith and other psychologists from the University of Utah.
"Women who are hostile are more likely to have atherosclerosis [hardening of the coronary arteries], especially if their husbands are hostile too," Smith says. "The levels of dominance or control in women or their husbands are not related to women's heart health."
"In men, the hostility - their own or their wives hostility during the interaction - wasn't related to atherosclerosis," he adds. "But their dominance or controlling behavior - or their wives dominance - was related to atherosclerosis in husbands." Smith summarizes: "A low-quality relationship is a risk factor for cardiovascular disease."
Smith conducted the study with University of Utah psychologists Cynthia Berg, a professor; Bert Uchino and Paul Florsheim, both associate professors; and Gale Pearce, a Utah postdoctoral fellow now on the faculty of Westminster College in Salt Lake City.
The study - which began in 2002 and ended in 2005 - involved 150 married couples with at least one member between 60 and 70 years of age and the other one no more than five years older or younger. The couples were recruited through newspaper advertisements and a polling firm. Those who participated had no history of cardiovascular disease and were not taking medicine for it.
Each husband and wife was paid $150 to participate, and also received free of charge a $300 CT scan to look for calcification in their coronary arteries - the arteries that supply the heart muscle and that can cause a heart attack when clogged. Smith says that in otherwise healthy people, calcification represents hardening and narrowing of the arteries that puts them at risk for later heart attack.
Each couple was told to pick a topic - such as money, in-laws, children, vacations and household duties - that was the subject of disagreements in their marriage. Then, while sitting in comfortable chairs and facing each other across a table, each couple discussed the chosen topic for six minutes while they were videotaped.
Psychology graduate students coded the videotaped conversations so that "each comment that reflected a complete thought" was given a code indicating the extent to which it was friendly versus hostile, and submissive versus dominant or controlling.
For example, comments like, "You can be so stupid sometimes" or "you're too negative all the time," were coded as hostile and dominant. Another dominant or controlling comment would be, "I don't want you to do that; I want you to do this."
"A warm, submissive comment would be, 'Oh that's a good idea, let's do it,'" Smith says. "A less warm one would be, 'If it's important to you, I'll do what you want.' An unfriendly, submissive comment is, 'I'll do what you want if you get off my back.'"
Smith says some of the marital discussions were calm and peaceful, but in some cases, the couples were quite hostile, prompting the psychology graduate students to refer them to marriage counseling. The researchers assumed that a couple's behavior during the discussion reflected their long-term pattern of behavior, although a marital spat in front of researchers likely "is a muted version of what goes on at home," Smith adds.
Two days after their discussion, each couple underwent a CT scan of the chest at the University of Utah's Center for Advanced Medical Technologies. Doctors used a standard scale to score each person's level of coronary artery calcification - an indicator of atherosclerotic plaque buildup in the arteries that supply blood to the heart.
Since the participants were healthy, none of the "silent" atherosclerosis revealed by the CT scans amounted to a medical emergency. "But there were people who had scores high enough they needed to discuss it with their doctor, because statistically it placed them at a high risk of a coronary event," Smith says.
The researchers found:
- The more hostile the wives' comments during the discussion, the greater the extent of calcification or hardening of the arteries. And "particularly high levels of calcification were found in "women who behaved in a hostile and unfriendly way and who were interacting with husbands who were also hostile and unfriendly."
- The extent to which either wives or husbands acted in a dominant or controlling manner was unrelated to the severity of hardening of the arteries in the wives.
- The extent to which wives or husbands spoke with hostility had no relationship to the severity of hardening of the arteries in the husbands.
- Husbands who displayed more dominance or controlling behavior - or whose wives displayed such behavior - were more likely than other men to have more severe hardening of the arteries.
"Another way to say it is that either being controlling or being married to someone who is controlling is enough to promote atherosclerosis in men," says Smith "So in couples where there was not a struggle for control - where it wasn't a contest - those men had much lower levels of atherosclerosis.
To sum it all up, hostility during marital disputes was bad for women's hearts, while controlling behavior during marital disputes was bad for men's hearts.
"Disagreements are an unavoidable fact of relationships," says Smith. "But the way we talk during disagreements gives us an opportunity to do something healthy."
"If you were concerned about men's heart health, you would ask couples to find ways to talk about disagreements without trying to control each other. If you were concerned about women's heart health, you would encourage couples to find ways to have disagreements that weren't hostile."
And for spouses concerned about each other, avoid both hostility and controlling behavior during disagreements, he adds.
Previous research indicates "close relationships are good for our heart health. Having relationships places you at lower risk than feeling lonely and isolated," Smith says. But the new study suggests "that the quality of those relationships is important."
In addition, "the dimensions of quality that are important differ for men and women. Conventional views of harmony versus discord - how warm versus hostile interactions are - are indeed important for women. But a different dimension of quality is more important for men, and that has to do with power and control in relationships."
Smith says a common factor is anger: wives' anger from feeling hostility or being subject to hostility; and husband's anger from experiencing or at least perceiving a challenge to their sense of control.
That "certainly is consistent with a large body of prior literature on emotions, relationships and health," he adds. "What's novel about this study is taking a snapshot of how couples talk to each other and relating that to a silent, progressive and potentially deadly disease."
Smith also offers another caution about the findings.
"People get heart disease for lots of reasons," he says. "If someone said, 'What's the most important thing I can do to protect my heart health?' my first answers would be, 'Don't smoke,' 'Get exercise' and 'Eat a sensible diet.' But somewhere on the list would be, 'Pay attention to your relationships.'"