Married people generally have better health than others, studies have found. (Alamy Stock Photo)

Is hostility in your marriage stressing or depressing you? Does your partner have a chronic disorder? Then watch out. Although married people generally have better health than others, studies have found, partners in these two situations can face an increased risk of obesity and cardiovascular disease.

Janice K. Kiecolt-Glaser, director of the Institute for Behavioral Medicine Research at Ohio State University, and Stephanie J. Wilson, a postdoctoral researcher in her lab, study — and explain here — the health effects of intimate relationships. The interview has been edited for length and clarity.

Q:  Is it true that, overall, being married is good for you?

JKG: A bunch of studies show that marriage, on average, is beneficial for rates of disease, recovery from surgery, cancer risk — most of the things you can look at. The effects of being single are similar in magnitude to the health risks of smoking, high blood pressure, obesity or a sedentary lifestyle.

SJW: A recent analysis showed that the effect of a quality marriage on physical health was about equivalent to that of daily exercise or a healthy diet.

Q:  Now the flip side. Studies show that a person’s risks for obesity, diabetes and metabolic syndrome rise dramatically if their partner has the condition — doubling in the case of obesity , for example. What explains this contagion?

JKG: If your partner has less-healthy behaviors, it gives you license, and perhaps subtle social pressure, to adopt them as well.

Q:  Being stressed by ongoing marital discord also aligns with poor health. What are common effects?

JKG: Cardiovascular disease has been well described, hypertension has been described — the whole metabolic-syndrome group of diseases. Marital discord doubles the risk for metabolic syndrome.

SW: A lot of the chronic illnesses that develop at higher rates in couples who are unhappy than in satisfied couples may be caused in part by inflammation.

Also, marital distress and depression are strong fellow travelers. An unhappy marriage is really, really fertile ground for depression, and depression has very well-documented health consequences.

Q: It sounds as if most roads lead through inflammation.

JKG: It’s one of the central pathways we know the most about these days, although there are certainly others. Inflammation is associated with a variety of different diseases.

Q:  Behaviors also change as a result of marital stress. How do they link to ill health?

JKG: Most of us don’t tend to eat more broccoli when we’re stressed, or all the things our mothers told us to do: Eat healthily, exercise, drink moderately. Those are all behaviors that, with stress, get worse.

SW: Sleep is particularly important for health, too, and is disrupted by marital stress.

Q:  Can these effects contribute to inflammation?

JKG: All the behaviors we’ve been talking about are also lovely for inflammation. When you are eating a high-fat, unhealthy diet, it’s inflammation-producing. Drinking heavily, smoking, sedentary behavior — they are all associated with inflammation. Depressive symptoms have inflammatory consequences, too.

SW: Sleep disorders are also associated with much higher levels of inflammation.

Q:  How does one show that marital discord affects physiology?

JKG: In the earlier studies in our lab, we would bring couples in and put a catheter in their arm and ask them to discuss a disagreement, and we could watch stress hormones in the blood respond to the quality of the disagreement. When people were more nasty or hostile, we would see much larger increases in stress hormones.

Q:  What behaviors do you look for, specifically?

JKG: Bad marriages often have the same kinds of symptoms. One classic signature is the demand-withdraw pattern, where one person will be saying they want a change and the other person doesn’t want to discuss it. Another signature is negative escalation: One person says something negative, the other person responds in kind, and it goes up and up and up.

Q:  Do you see gender differences in responses to marital distress?

JKG: There is a large psychological literature showing that women remember both positive and negative events in much more detail than men; women ruminate or think about those relationship events much more than men. So it would be surprising if there were not greater health effects for women.

Q:  At the other end of the spectrum, having a really good relationship can put a person at risk for health problems if the partner is ill. What goes on there?

JKG: Some of the best evidence comes from the extreme case of spouses caring for partners with Alzheimer’s disease. Years ago, we showed that the spouses’ immune systems were less likely to respond to vaccination as they should; spouses’ wounds healed more slowly; they had higher levels of inflammation. There is now good evidence across less-dramatic illnesses that a spouse’s illness matters.

Q:  Elderly couples in a happy marriage face a greater health risk than younger people do when a partner is ill. Why?

JKG: Older couples have longer, more-intense relationships. Also, the older someone is, the more vulnerable they are physiologically. Stress for someone in their 20s is not likely to make them sick or have huge health effects, but we know that when someone is 65 or 70, noticeable declines in the immune response begin, and age-related increases in inflammation.

SW: In general, as people age, there is a decrease in the size of the social network. Psychological weight is placed on the marital relationship.

Q:  Is there a good way to protect health when couples have marital problems?

JKG: There is some evidence that marital problems are going to be most responsive to marital therapy (as opposed to individual therapy). It can address the utility, or lack of utility, of the way couples are thinking about particular problems.

SW: And it can encourage making an effort to take the other person’s perspective and to approach problems as a team. We only have a few studies to look to. But they’ve shown that if the therapy is effective at reducing marital problems, we see a reduction in stress hormone reactivity.

Q:  To limit marital tension when one partner is ill, the advice to a spouse seems to be “Be supportive.” But how do you do that without seeming to be a nag or too critical?

SW: Supporting the person in their independence — essentially saying, “I believe in you; this is a challenge, but you can do this” — can build a partner’s self-confidence. Being empathic has also been shown to be effective — listening actively when the partner wants to share, and being generally loving and warm.

Q:  In your own relationships, have you used anything you’ve learned from the research?

JKG: Yes — the idea that you pay attention to your relationship; that it matters how you talk about it and think about it. And it matters that you take good care of yourself, as well as attending to your partner, when your partner is ill.

My husband has Alzheimer’s disease. When he was first diagnosed with mild cognitive impairment, I saw the train coming down the tracks. Our lives were very much intertwined. He was my primary research collaborator, and we had a really good relationship and a closeness.

So I tried to make sure that I had my own life aside from the marriage, in terms of friendships, and I tried very hard to take care of my own health. I knew all too well what happened when people didn’t take care of themselves.

Q:  Don’t breakups cause anxiety, depression and stress, too? And loneliness? Which is worse for health — staying in a non-ideal relationship or going it alone?

SW: The evidence is mixed. One study found that singles had lower resting blood pressure than unhappily married people. But a study of people with rheumatoid arthritis found that singles and the unhappily married were in an equal amount of pain. In both cases, happily married people fared best.

As for divorce, most people cope well and recover quickly post-marriage, but a consistent minority (10 to 15 percent) struggle and face heightened health risks.

And as for loneliness, it is possible to feel lonely in a marriage. In the unmarried, surrounding oneself with other friends and family seems to be especially important.

Rusting is a science writer and editor. This article first appeared in longer form at Knowable Magazine.