|A couple getting married is seen silhouetted in an undated photo.
There is even more proof that an unhappy marriage is bad for your health, researchers said.
The stress that comes from discord appears to slow the initial production of a blood protein that is key to healing wounds, the report from Ohio State University said.
Quarreling couples studied in a laboratory setting had a slower wound healing process than when they were not arguing, as measured by how rapidlyblistershealed. The blisters were deliberately inflicted on the test subjects by using a vacuum pump on the arm.
"Couples who demonstrated consistently higher levels of hostile behaviours ... healed at 60 percent of the rate of low-hostile couples," said the report published in the December issue of the Archives of General Psychiatry.
The authors said there is already a sizeable body of research showing that marital disagreement causes adverse health impacts ranging from high blood pressure and depression to the ability to cope with heart disease and heart failure.
"Although loss of a spouse can provokeadversemental and physical health changes, the simple presence of a spouse is not necessarily protective. A troubled marriage is itself a prime source of stress," the study said.
The Ohio State study involved 42 married couples, aged 22 to 77. They were tested twice -- first in a social setting and then again when they were told to get into disagreements.
The authors said stress appears to slow the local, wound-site production of proinflammatory cytokines -- protein molecules produced by white blood cells that play a key role in the early stages of healing.
But the study also found that couples with high degrees of conflict had higher levels of the same cytokines generally in the bloodstream the morning after an argument, compared to those who were not in as much disagreement.
While greater early production at wound sites is beneficial, the authors said, a higher systemic level is harmful.
"Elevated levels of proinflammatory cytokines have been linked to a variety of age-related disease, including cardiovascular disease, osteoporosis, arthritis ... certain cancers, and frailty and functional decline," the study said. "Moreover, inflammatory activation can enhance development of depressive symptoms."