Upcoming research suggests that a bad marriage can lead to an 8.5 percent greater risk of suffering heart attack or stroke than those with a surfeit of good feelings in marriage.

“Growing evidence suggests that the quality and patterns of one’s social relationships may be linked with a variety of health outcomes, including heart disease,” said Thomas Kamarck, study author and professor of psychology and Biological and Health Program Chair in the University of Pittsburgh Kenneth P. Dietrich School of Arts and Sciences.

“The contribution of this study is in showing that these sorts of links may be observed even during the earliest stages of plaque development (in the carotid artery) and that these observations may be rooted not just in the way that we evaluate our relationships in general, but in the quality of specific social interactions with our partners as they unfold during our daily lives.”

Unhappy marital interactions have been correlated with thicker carotid arteries and a higher risk of cardiovascular disease.

“These findings may have wider implications,” says Nataria Joseph, who recently completed a postdoctoral fellowship under Kamarck and is the lead author of the paper.

“It’s another bit of support for the thought that marital or serious romantic relationships play a significant role in overall health. Biological, psychological, and social processes all interact to determine physical health.”

The study was conducted on 281 married healthy, employed, middle-aged adults. The study also included those living with a partner in a relationship that was very similar to marriage. Their interactions were closely observed hourly over the course of four days.

Also, the subjects were asked to rate those interactions as ones that were either positive or negative.

Partners with more negative interactions were found to have thicker carotid. Those are major factors in heart health, because they supply the neck and head with oxygen-filled blood.

The findings were consistent regardless of demographic factors such as age, gender, race, and education level.

Heart health may not only be associated with biological and physical factors, emotional well-being also contributes to a healthy heart.

“What it does show,” said Joseph, “is that health care providers should look at relationships as a point of assessment. They are likely to promote health or place health at risk.”

The study was published in this month in the journal Psychosomatic Medicine.