An unhappy marriage may impact your heart in more ways than one.

A new study out of the University of Pittsburgh finds that people in unhappy unions are at a higher risk of being diagnosed with a heart ailment. Indeed a troubled marriage is linked to thicker carotid arteries, which carry blood directly to the brain.

"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," researcher Thomas Kamarck, professor of psychology at University of Pittsburgh, said in a press release.

"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)," he added. "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."

The study found that those with negative marital interactions may have an 8.5 percent greater risk of suffering heart attack or stroke than those with positive ones.

Nataria Joseph, lead author of the study, noted in a press release that: "These findings may have wider implications. 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 looked at 281 healthy, employed, middle-aged adults who were married or living with a partner in a marital-like relationship. Their interactions were monitored hourly over the course of four days, with the partners rating their interactions as positive or negative.

Carotid artery thickness was also measured. Those partners reporting more negative interactions were found to have thicker carotids. Joseph said that nothing else could account for these associations. The findings were consistent across age, sex, race and education level.

However, Joseph noted that there are some limitations to the study because all the data was gathered at one point in time. Causality, therefore, has not been proven, though a strong correlation has been established.

"What it does show," she said, "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."

Over the years, many studies have found married people to live longer than their single counterparts. More specifically, research has linked marriage with a lower risk of developing cancer, having a heart attack and being diagnosed with dementia and various diseases.

But there also has been some good news for singles, too. Research has shown that unmarried people with active lifestyles enjoy their own health benefits.