Oct. 8, 2007 -- Marriages and close friendships marked by negativity -- such as conflict and adverse exchanges -- boost the risk of heart disease, according to a new study.
"Those in a negative relationship were 34% more likely to have a coronary event in the 12 years of follow-up," says Roberto De Vogli, PhD, MPH, a researcher for the study, published in the Archives of Internal Medicine.
Even after taking into account other factors that could contribute to heart disease, such as depression, men and women with negative aspects in relationships still had a 25% increase in heart disease risk over the follow-up period, says De Vogli, an epidemiologist at University College London. "We found the effect is there not only for married people," he says, but also for unmarried people who have negative relationships with close friends.
Putting It in Perspective
In past research, De Vogli tells WebMD, many researchers have found that social relationships, including marriage, are associated with better health and less cardiovascular disease. "The more friends, the better" has been the assumption.
Yet there were contradictory findings, he says, on the health benefits of social support and the limited protective effects of being married on heart disease risk among women.
"We expanded the debate [to be] about the quality of social relationships rather than the quantity," he says.
A Closer Look
De Vogli's team asked 9,011 British civil servants, on average in their mid-40s, to complete a questionnaire either between 1989 and 1990 or 1985 and 1988. They answered questions about up to four of their close personal relationships, but mostly about their primary relationship.
More than 64% listed their spouse as their primary relationship. "Others were close personal friends," De Vogli says of the unmarried respondents.
The questions asked about the amount of emotional and practical support respondents got from their relationships and about interactions. For instance, they were asked how much stress or worries the spouse or friend caused them in the past 12 months, how much talking to the person made situations seem worse, how much the respondent would have liked more practical help from the partner or friend, and how much more the person would have liked to confide in the partner or friend, among other questions.
During the follow-up period of about 12 years, heart disease was reported by 589 men and women of the 8,499 respondents who finished the questionnaires. None of the 8,499 respondents had any history of heart disease at the start of the study.
Those who had high negativity in their marriage or close friendship -- such as saying that talking to the partner or friend about problems made things seem worse -- were 34% more likely to have a heart problem compared with those with more positive interactions and low level of negativity. The increased risk dropped to 25% after taking into account other variables that could contribute to heart disease such as depression.
De Vogli didn't find an association between the level of practical support or emotional support and heart disease risk.
What's behind the bad marriage -- bad heart link? People may mentally "replay" the negative interactions, De Vogli and other researchers suspect. "It can activate emotional responses, including depression or hostility," he says, in turn boosting heart disease risk. De Vogli found the association held for both men and women and for those in higher and lower social positions. More likely to have negative relationships, he did find, were those in lower-grade jobs. Negative close relationships were less likely in people who were never married.
"It's an intriguing finding," says Robert Allan, PHD, a clinical assistant professor of psychology in psychiatry at New York-Presbyterian Hospital/Weill Cornell Medical Center. He reviewed the study for WebMD.
"In this study, they controlled for many variables [that could contribute to heart problems], including age, sex, marital status, high blood pressure, and diabetes," says Allan, an expert in the field of anger management with a specialty in coronary risk reduction.
Overall, he says, the link De Vogli's team found between negative relationships and heart disease is not "huge." Still, "this is one study that adds to a significant database suggesting that negative effect is bad for both quality of life and for the heart."
It's a wake-up call to work on improving relationships as one way to improve cardiac health, says Allan.