An unhappy marriage could quite literally break your heart, new research suggests

People in unhappy marriages could be more at risk of heart disease.

A bad marriage really could lead to a broken heart, new research looking at how marriage quality affects cardiovascular health suggests.

A study by US researchers found older couples who are in an unhappy marriage have a higher risk of heart disease than those in a happy marriage.

A team at Michigan State University and the University of Chicago said the risk is greatest for married women aged between 70 and 80-years-old.

The team analysed five years of data from 1,200 married men and women who participated the National Social Life, Health and Aging Project. The participants were aged between 57 and 85-years-old at the beginning of the project.

The men and women had been asked questions about the quality of their marriage and their cardiovascular health, such as whether they had experienced heart attacks, strokes or high blood pressure as part of the project.

Sociology professors Hui Lui and Linda Waite examined the relationship between marital quality and heart disease and whether any relationship varies depending on age or gender.

Lui said negative marital quality, such as husbands and wives being overly critical or demanding, had a bigger effect on heart health than positive marital quality, such as spouses being supportive.

"In other words," the research said, "a bad marriage is more harmful to your heart health than a good marriage is beneficial."

The effect marital quality has on heart health becomes much stronger with age. The team found the stress resulting from a bad marriage may stimulate more, and more intense, cardiovascular responses of the increasing frailty and declining immune function that develops in old age.

Lui said marriage quality had a bigger impact on women's heart health, which may be because women tend to "internalize negative feelings", making them more likely to be depressed.

"Marriage counselling is focused largely on younger couples," said Lui. "But these results show that marital quality is just as important at older ages, even when the couple has been married 40 or 50 years."

The study 'Bad marriage, broken heart? Age and gender differences in the link between marital quality and cardiovascular risks among older adults' is published in the Journal of Health and Social Behaviour.

- Independent