(REUTERS HEALTH) - When older men have stressed-out wives, their own blood pressure may go up, a U.S. study suggests.

While previous research has linked stress and bad relationships to elevated blood pressure, less is known about how these challenges affect both members of a couple, and how the spouses affect one another, over time.

For the current study, researchers evaluated about 1,350 couples once in 2006 and again in 2010 to see how each person’s blood pressure might change based on shifts in their relationship satisfaction or stress levels.

"We found that husbands had higher blood pressure when wives reported greater stress and that this link was even greater when husbands felt more negative about the relationship," lead study author Kira Birditt, a scientist at the Institute for Social Research at the University of Michigan in Ann Arbor, said by e-mail.

"In addition, negative marital quality experienced by only one member of the couple was not associated with blood pressure, but when both members of the couple reported higher negative marital quality they both had higher blood pressure," added Birditt.

About one in three U.S. adults has high blood pressure, according to the National Institutes of Health.

Birditt and colleagues reviewed data from a nationwide sample of 22,000 people born in 1953 or earlier, focusing on a subset of opposite-sex couples with both members having participated in face-to-face interviews about their relationships.

Compared to the larger group, the subset in this study was healthier, younger, more likely to be white and report less chronic stress. Most couples were married, but 3% were cohabitating.

In 2006, about one third of husbands had high blood pressure, as did 26% of the wives. By 2010, 37% of the men and 30% of the women had high blood pressure.

Stressed out husbands had lower blood pressure when their wives reported less stress, the study found. The stressed out women, however, had lower blood pressure when their husbands were also under a lot of stress.

The wives’ stress was more likely to be linked to high blood pressure in their spouses when the men were unhappy with the relationship.

The study only used four questions to assess relationship quality, which might miss some nuances that could impact the results, the researchers acknowledge in their April 7 online report in the Journals of Gerontology, Series B.

There is mounting evidence that exposure to stress, including negative relationships or marriages, is related to poor physiological outcomes, Kristen Peek, a professor of preventive medicine and community health at the University of Texas Medical Branch in Galveston, said by e-mail.

"Older husbands tend to be dependent on their wives for care, defined broadly as meal preparation, household responsibility and caregiving," said Peek, who wasn’t involved in the study.

For older couples whose marriages follow more traditional gender roles, it makes sense that "older husbands would have decreased mental and physical health in response to their wives decline," Peek said.

May 26, 2015