Older couples who are in a bad marriage are more likely to suffer from heart disease than those in a healthy relationship.

The findings suggest marriage counseling programs should work to promote marriage quality for couples in their 70s and 80s, Michigan State University reported.

"Marriage counseling is focused largely on younger couples," said Hui Liu, a Michigan State University sociologist. "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."

To make their findings the researchers looked at 1,200 married men and women who participated in the National Social Life, Health and Aging Project and were between the ages of 57 and 85.

The analysis included survey questions that determined marital quality as well as lab tests and self-reported measures of cardiovascular health, such as "heart attacks, strokes, hypertension and high levels of C-reactive protein in the blood."

The researchers determined negative marital quality has a larger effect on heart health in older couples than positive marriage quality (such as spousal support). This means a bad marriage has more of an influence on heart health than a good one.

The link between marriage quality and cardiovascular risk also appeared to grow stronger with age. The findings also suggested marital quality has a bigger effect on women's hearts than men's, most likely because women are more likely to internalize negative feelings, which can lead to depression. Heart disease proved to lead to a decline in marital quality for women, but not men; this is consistent with past findings that wives are more likely to take care of husbands when they are sick than vice versa.  

"In this way, a wife's poor health may affect how she assesses her marital quality, but a husband's poor health doesn't hurt his view of marriage," Liu said.

The finding was published in a recent edition of the Journal of Health and Social Behavior.