People everywhere are living longer than ever. The average global life expectancy has more than doubled since 1900 and now exceeds 70 years. Vaccines and antibiotics have reined in scourges like polio, tuberculosis and pneumonia, which can strike young and old people alike. This helps explain why diseases that have long been more common in the elderly, such as cancer and cardiovascular ailments, are today leading causes of mortality, making up more than 35 percent of all deaths. In the United States, roughly half of all adults suffer from at least one sort of ongoing, incurable illness, including cancer, multiple sclerosis, rheumatoid arthritis and diabetes.

Considering how painful and disabling these conditions can be, it’s no surprise that people with chronic illnesses are two to three times more likely than the general population to suffer from depression. That risks a downward spiral in which a patient may stop keeping up with treatments and other self-care, such as diet and exercise, and sink further into despair as health inevitably declines. Yet people differ dramatically in the way they respond to being ill. While some surrender hope, others become determined to do all they can to maintain or improve their health, with some even finding silver linings in their diagnoses.

Vicki Helgeson, a psychologist at Carnegie Mellon University, in Pittsburgh, Pennsylvania, has spent more than 25 years studying how people adjust to chronic illness. “Most people are amazingly resilient and find successful ways of coping with whatever stressors life throws their way,” she says. Still, a large minority with the same severity of illness will suffer more, both physically and emotionally. Studies show that the factors that make the difference include gender, personality traits and, perhaps most importantly, relationships with friends, family and peers.

Writing in the 2017 Annual Review of Psychology, Helgeson and graduate student Melissa Zajdel described evidence from more than 150 studies analyzing what makes some people more resilient and others more vulnerable to chronic illness. Knowable recently spoke with Helgeson about what she has learned from that literature as well as from her clinical experience supporting chronically ill patients. This conversation has been edited for length and clarity.

Why is there such a wide range of outcomes for people living with chronic illness?

How patients fare after being diagnosed with chronic illnesses depends a lot more on them than on their doctors. The patient has to be taking medication, monitoring diet, exercising and following up with medical appointments, all of which can make a big difference in how well he or she does, both psychologically and physically.

At the same time, having a chronic illness will mean different things to different people, and to different people at different stages of the disease. For some people, having a chronic illness completely changes the way they think about themselves; among people who are equally physically impaired, some will see themselves as much more altered than others. For instance, one study of men with prostate cancer showed that one-third said they felt less masculine. In a study comparing heterosexual women and lesbians with breast cancer, the lesbians reported less concern about their appearance.

How many people are we talking about?

These are big numbers. About 85.6 million people in the United States are living with some cardiovascular disease or the aftereffects of a stroke. Some 14.5 million have a history of cancer or are living with cancer. And roughly 29.1 million have been diagnosed with diabetes.

Additionally, some 24 million US adults, more than 10 percent of the adult population, are limited in their activities because of arthritis. Just over 1 million are living with HIV, and another 1 million people have been diagnosed with multiple sclerosis.

How did you come to be interested in this subject?

I’ve been interested in gender and health for many years. Back in graduate school, I wrote my dissertation on the role of masculinity in heart disease; I was really intrigued by the ways we socialize men that might harm their health. For instance, we encourage men to be independent and physically and mentally strong, which translates into men not seeking help when they need it, whether that help is going to a doctor or simply disclosing a problem to someone.

In more recent years I’ve zeroed in on the personality traits of “agency” and “communion” in health, in particular “unmitigated agency,” more often found in men, which is a focus on the self to the exclusion of others, and “unmitigated communion,” more often found in women, which is to focus on others to the exclusion of self. Both of these characteristics can play a large role in physical health in general and in particular how someone copes with chronic illness. For example, a woman who is chronically ill will often try to continue to care for her family, even at the cost of caring less well for herself.

Many of the studies you cite indeed suggest that gender makes a big difference when it comes to chronic illness, both in the kinds of illnesses we get and the way we react to them.

Research shows that compared to men, women have more nonfatal chronic illnesses, mainly autoimmune diseases such as lupus, rheumatoid arthritis and multiple sclerosis, while men have more chronic illnesses that are likely to be fatal, such as heart disease and cancer. So overall, women live longer than men, but women are also more likely than men to live with disease.

And you have also found that, in general, women who are chronically ill have a harder time with it emotionally than do men.

We did find this to be the case, but it’s complicated. It’s true that when women are chronically ill — for instance with something like type 2 diabetes — on average and compared with men, women report being more depressed and more physically limited due to the illness. (There are a few exceptions to this rule: One study showed that men with heart failure perceived their health as being worse than women with similar illness.)

The complication is that even when we’re physically healthy, women suffer more from emotional problems than do men. In the general population, women are twice as likely as men to be depressed. So I can’t say that women with chronic illnesses are more depressed than men due to the illness, specifically. The research just isn’t clear. What I can say is that the way we socialize males versus females can have a negative impact on how both men and women adjust to chronic illness. For women, the issue is that we may try to resume our role as caregivers. For men, the issue is they may try to appear strong and self-reliant and be unwilling to ask for help.

One particularly striking finding you report is that a woman will suffer more than a man whether she herself is ill or is caring for a man with a chronic illness.

This may be because, in general, women are socialized to be more other-focused than men, while men are socialized to be more self-focused. If you’re more other-focused, it may be more difficult for you to take care of yourself when you’re ill. You may also be more vulnerable to emotional contagion when your spouse is ill.

Wasn’t the feminist revolution supposed to have done away with all that self-sacrificing?

There have definitely been some changes. Women are socialized now to have more agency and be more assertive — but not at the expense of giving up that “other” orientation.

What about race as a factor in how people fare with chronic illness?

It clearly has an effect. Black people with diabetes, for instance, on average report greater distress related to their condition and greater interference with their daily activities than do whites with the same illness. Non-whites with heart disease on average have a greater decline in functioning over five years. But it’s hard to get clear explanations of what is happening here, since race and ethnicity may also be linked to lower incomes and the unhealthy environmental conditions that can come with them, from more pollution to poor-quality medical care.

When you think back on all the research you have done, including for your review article, what has most surprised you about how people cope with chronic illness?

I’ve been struck by how important it is for someone facing a diagnosis to have some sense of control. People who have a high sense of control tend to believe that they can influence their health. So when faced with chronic illness, a person with a high sense of control is more likely to take actions that might actually influence the course of their disease — such as taking medication and exercising, and so on.

You can’t control everything of course, and you don’t really get to decide what you can control, but when you figure out what you can, it enhances your feelings of self-worth and reduces distress. It’s like the Serenity Prayer, about accepting what you can’t change while having the courage to change what you can and the wisdom to know the difference. And then you might ask, what happens if treatment fails and the disease comes back? Are you worse off having believed you had control? No, you’re not. It’s always better to figure out a way to have some control. If you have a high sense of control over what happens to you, you’ll try harder to take care of yourself and manage the disease.

I remember meeting a woman who was undergoing angioplasty, a procedure intended to open the coronary arteries. Some portion of these operations fail in the sense that the benefits don’t last that long. After three months, the problem returned, and she chose to try angioplasty for a second time. It again failed to take. She then had a third angioplasty, and once again ended up requiring further treatment. Finally she had bypass surgery, and you might think she’d have said should have just had the bypass surgery at the beginning, but instead she said, “I’m just thrilled there was another available treatment!” That kind of attitude can be quite helpful. I don’t know if people with that attitude live longer, but they’re happier and healthier while they’re living.

What other sorts of attitudes can make a difference?

I subscribe to Shelley Taylor’s cognitive adaptation theory, which characterizes the kind of person most able to deal with a chronic illness. Generally, it’s the kind of person who has a high sense of self-esteem and self-worth, who sees his or her life as worthwhile. This kind of person may even be more likely to find benefits in the seemingly bad news of a diagnosis.

Twenty years ago I did a lot of work on breast cancer. A common response was for women to say, quite seriously, that it was the best thing that ever happened to them. One woman actually said that given a choice between cancer and winning the Tour de France, she’d choose cancer, because she had learned so much from it. Another said her illness had inspired her to leave her husband — she wouldn’t have done that otherwise. Someone else might say having a heart attack was a blessing that brought him closer to his family, made him slow down at work and pay attention to more important things. With respect to diabetes, someone might say I now pay more attention to myself, to exercising and eating better.

But what do you think about Barbara Ehrenreich’s argument in her book, Bright-Sided: How the Relentless Promotion of Positive Thinking Has Undermined America? She wrote it after being diagnosed with breast cancer, when she says she was made to feel that if she didn’t get better, it was her fault for not being optimistic enough.

Yes, I agree that can be harmful. It’s helpful for people to find the good in the bad, but doing so can actually also be a form of avoidance. It’s a problem we have in our culture where we don’t want to hear about bad news and stress, and then someone might react against that, saying, “This is crazy; I’m trying to tell you I’m upset about something and you say I should just focus on the good things.”

There are data that show this can be distressing to people with cancer. It makes them feel not validated and not heard. People want to be able to disclose their concerns and feel listened to and understood — they don’t want people to invalidate their feelings by trivializing their problems or telling them to cheer up.

So is there one single thing that can make the most difference in how we cope with chronic illness?

Yes! Having good relationships! It’s very important to find at least one person who will listen to you and let you be yourself. They don’t have to have the same illness.

There is a lot of research showing that being embedded in a social network is good for psychological health and physical health. And there are all kinds of reasons for that. Being involved in relationships means that there is someone to notice if you are having a problem, someone urging you to go to the doctor or encouraging you to eat healthy food, someone depending on you, which motivates you to take care of yourself, someone to listen to you, someone to depend on for assistance. Not everyone has this in their lives, which is unfortunate, as some large-scale studies have even linked such relationships with reduced mortality.