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: