The nature of loneliness

Chicago psychologist John Cacioppo digs for the roots of social isolation and its effects on health and humanity.

By Lydialyle Gibson
Illustrations by Polly Becker; photo by Dan Dry

Two years ago, Chicago psychologist John Cacioppo wrote a book about loneliness, about how the need for social connection is so fundamental in humans that without it we fall apart, down to the cellular level. Over time blood pressure climbs and gene expression falters. Cognition dulls; immune systems deteriorate. Aging accelerates under the constant, corrosive presence of stress hormones. Loneliness, Cacioppo argued, isn’t some personality defect or sign of weakness—it’s a survival impulse like hunger or thirst, a trigger pushing us toward the nourishment of human companionship. Furthermore, he wrote, “people who get stuck in loneliness have not done anything wrong. None of us is immune to feelings of isolation, any more than we are immune to feelings of hunger or physical pain.”

Not long after Loneliness arrived in bookstores, the letters and e-mails started coming in. One after another, readers opened up about spouses they’d lost and friends they lost touch with, divorces that cost them families of in-laws, the isolation they’d felt in new jobs or new cities, at home with new babies, or for no reason they could name. Some people wrote with questions about particular aspects of his research; others just wanted to share their stories. “I still get e-mails all the time,” says Cacioppo, who coauthored the book (published by W. W. Norton & Company) with science writer William Patrick. Those who feel stigmatized are grateful to find out they’re not at fault—and that they’re not alone: 20 percent of Americans, about 60 million people, Cacioppo estimates, suffer from loneliness that is chronic and severe enough to be a major source of unhappiness.

When he can, he writes back. Even before Loneliness came out, Cacioppo got letters from people who happened across his research in magazine and newspaper stories. One woman, whom Cacioppo quoted in the opening pages of the book, wanted to know how to “resolve the inner feeling of being alone.” She went on to ask: “If and when you find any answers, please write back and tell me.”

Over the past two decades, questions about loneliness—how it evolved, how it works, how to fight it—have increasingly consumed Cacioppo. His immersion has reached the point, he says, where it “makes me a little bit embarrassed.” He never thought his research focus would be so singular. The founding director of the University’s Center for Cognitive and Social Neuroscience, and a founder of social neuroscience itself, Cacioppo had written in the past about a range of subjects: attitudes and persuasion, communication and social cognition, emotion, and cardiovascular psychophysiology. “I don’t study things for this long,” he says. “I tend to follow Fermi in the sense of, you study something for ten years, and at the end of ten years your contributions are so small that it’s time to do something else.” But loneliness is a deep well, and he’s fishing for the bottom. “This just continues to change how I think about us as a species.”

Being lonely isn’t the same as being alone. Cacioppo is careful to clarify this distinction in every public lecture and conference talk he gives (and there are many, usually pretty crowded). Lonely people, he’s found, are as likely as anyone to be surrounded by coworkers, neighbors, friends, and family. They’re no less attractive or intelligent or popular. What sets the lonely apart is a perceived isolation, the sense that their relationships do not meet their social needs. 

That uneasy feeling goes back eons. The earliest humans experienced it; loneliness was, Cacioppo believes, a powerful evolutionary force binding prehistoric people to those they relied on for food, shelter, and protection, to help them raise their young and carry on their genetic legacy. In the book he hypothesized that the distress they felt if they drifted toward the outskirts of their group served as a warning to reengage or else perish. Cacioppo also points to the long years children spend in abject dependence on their parents. “Even being conservative,” he says, “it’s a good decade before they’re going to be able to survive on their own.” Small wonder that isolation makes people feel not only unhappy but also unsafe.


Which is why, for the most part, loneliness works. Nearly everyone feels isolated and alone from time to time, but the majority emerge from that unpleasant state on their own. Feeling lonely after a friend moves away or a loved one dies prods people to reach out to those around them, to renew their ties or replace broken ones. Generally, Cacioppo says, “loneliness does seem to be working on its own in most people. Some people get stuck, but on average, when you get lonely—or when you’re in pain or when you’re hungry or you’re thirsty—you do something to get out of that aversive state.”

Like other evolutionary adaptations, loneliness varies from person to person. There are extroverts and introverts. There are those who don’t seem to need friends at all. “Some people do not feel strong pain by disconnection,” Cacioppo says. “That makes great sense, because those are the explorers. We need them.” But for those who feel warmer near the communal fire, isolation works as a civilizing influence. “It gives you the capacity to shape better social members of your species,” he says. In a chapter of the forthcoming Handbook of Social Exclusion (Oxford University Press), Cacioppo and Chicago psychologists Louise Hawkley and Joshua Correll offer the example of a child sent into the corner for misbehaving. “When a child is acting selfish and narcissistic, you put them by themselves,” Cacioppo says. “Well, that’s not a dramatic punishment, is it? And yet it’s painful.” Children cry; they beg to be allowed back into the group. When they do come back, “they’re better social citizens. They’ll now take the other child’s perspective; they’ll share their toys.” 

Questions of loneliness have consumed John Cacioppo for more than 20 years.

For a long time loneliness baffled scientists. It seemed paradoxical to natural selection, a phenomenon that contradicted the idea that only the fittest survive: persistently lonely people are unhealthy, depressed, withdrawn, hostile. They find ordinary social encounters threatening and push away the people who could help them. But scientists always looked at the condition on a “personal timescale,” Cacioppo says, rather than on an evolutionary one. For individuals, loneliness is brutal; for the species, it’s beneficial. He saw loneliness  as a “really good, strong model” for showing the interdependence of social and biological processes in human existence.

Cacioppo’s early interest in loneliness is a scientist’s story, not a personal one. “Unfortunately, it’s not like I had this lonely episode,” he says. “People are disappointed when they hear that.” In 1988 he read a Science paper whose conclusions seemed wrong to him. Three sociologists conducted an analysis showing that objective isolation—a lack of social contact—predicted death from a broad range of maladies. The researchers suggested that “social support” from friends and family might “foster a sense of meaning or coherence that promotes health” and encourage loved ones to exercise, eat better, sleep more, and drink less.

“But what I knew,” Cacioppo says, “was that no matter what social species you’re talking about, all the way down to fruit flies, if you isolate them they die earlier.” Scientists have shown that to be true of mice, rats, pigs, squirrel monkeys, rhesus monkeys, chimpanzees, and rabbits. A 2008 study by two biologists in the Proceedings of the National Academy of Sciences found that genetically impaired fruit flies survive longer in the presence of other flies. “That’s probably not due to social control from friends and family,” Cacioppo says. “There’s something more interesting and more direct.”

By the time he read the 1988 paper, Cacioppo had been researching social connection for years, becoming more and more interested in an area that would later be called social neuroscience. Still a new field, it challenges the idea that the nervous, endocrine, and immune systems operate outside the reach of cultural influences. “The abyss between biological and social levels of organization is a human construction,” explains Cacioppo’s laboratory website. Human biology “has evolved within a fiercely social world, provides potentials and constraints for representation and behavior attuned to this social world, and is shaped profoundly by the social world.”

Cacioppo and psychologist Gary Berntson gave social neuroscience its name, in a 1992 American Psychologist paper. At the time, Cacioppo and Berntson were colleagues at Ohio State; Cacioppo earned his master’s and doctorate there before joining the faculty in 1989 (he came to Chicago in 1999). In the article Cacioppo and Berntson pointed out that mental disorders such as depression, schizophrenia, and phobias are “both determined by and are determinants of social processes.” Addiction, juvenile delinquency, child abuse, spousal abuse, prejudice, worker productivity, and the spread of AIDS are “quintessentially social as well as neurophysiological phenomena.” So focusing narrowly on the biological or social yields only a partial picture. In primates, testosterone levels shape male tendencies toward sex and aggression, but social rank and the availability of females influence testosterone levels. “Social psychology, with its panoramic focus on the effects of human association,” wrote Cacioppo and Berntson, “is therefore a fundamental, although sometimes unacknowledged, complement to the neurosciences.”


Sixteen years later, Loneliness offered a 300-page demonstration of the link between social psychology and neuroscience. Since the book’s release, Cacioppo has worked to reinforce and extend its hypotheses. A February 2010 study of twins and their families, coauthored with European researchers, confirmed that loneliness is “moderately heritable.” Cacioppo puts the split at 50 percent genetic tendency and 50 percent environmental influences, although “we’re trying to figure out what specifically is being inherited.” Recently he finished an analysis showing that symptoms of depression associated with loneliness can long outlast the condition itself. “So if you’re chronically lonely this year, and then all the sudden that’s fixed,” he says, “you’ll still see the effects for two years.” The converse is also true: the emotional benefits of feeling connected persist for two years, even if those connections wither.

In 2002 Cacioppo launched a longitudinal study of middle-aged and older Americans around Chicago, tracking their health and daily habits. In the book he offered some preliminary results on the connection between loneliness and depression. Since then the study—still ongoing—has shown that loneliness predicts not only depression but also higher blood pressure and increased cortisol, a hormone released in response to stress. Although loneliness doesn’t shorten sleep duration, it does make sleep less restful, because of tiny, subconscious awakenings throughout the night. In loneliness, Cacioppo says, the brain still hears that ancient warning, and people are most vulnerable when they’re asleep.

Some of the most troublesome effects are cognitive. Analyzing the work of other researchers in a 2009 Trends in Cognitive Sciences paper, Cacioppo and Hawkley laid out evidence that social disconnection contributes to Alzheimer’s disease and impairs “executive functioning”—the ability to control thoughts, emotions, and impulses. “Loneliness leads to poor health behaviors, but only the impulsive kind, anything that could be damaging but that’s pleasurable,” Cacioppo explains. “So higher fat and sugar in your diet. And alcoholism, drug addiction, and less exercise.”

In the paper Cacioppo and Hawkley noted that lonely people show heightened focus on negative thoughts and perceptions. In fMRI studies, the region of the brain associated with rewards lights up more strongly in the nonlonely when they see pictures of happy social situations. Images of unpleasant social encounters more forcefully awaken lonely people’s visual cortices. In one Cacioppo experiment, described in Loneliness, participants were asked to name the color certain words were printed in. Lonely subjects, distracted by negative messages in words like “fear” and “compete,” took a split second longer than the nonlonely to identify the colors.

Lonely people tend to find greater fault with themselves and also those around them; they expect others to be less friendly, less kind. They’re bracing against “social threats,” but those expectations have a way of fulfilling themselves, Cacioppo says. In the negative-feedback loop of chronic loneliness, self-protection turns out to be self-defeat.

In talks and interviews, Cacioppo often cites a study in which sociologists asked respondents to list the number of confidants they had. In 1985 the most frequent answer was three. In 2004, when researchers repeated the survey, the most common answer had dropped to zero. One-fourth of participants, drawn from a cross-section of the American public, reported having no one to talk to intimately.

The reasons for the rise in social isolation are multiple and well documented: contemporary American life is less rooted, more hectic, more scattered. Jobs and friendships are transitory; divorce rates are high, as is the number of single-parent households. More people move away from home, and more people live alone—that number has increased by 30 percent in the past 30 years, Cacioppo says.

Onto this landscape, social media erupted—Facebook, MySpace, Twitter, LinkedIn—exerting an influence more complicated, Cacioppo says, than some people might think. “If you’ve got a disability and you can’t get out, social networking is a great boon.” People who use the Internet to generate or enhance in-person relationships also benefit, he says. But when others use online connections to substitute for face-to-face ones, they become lonelier and more depressed. Lonely people are likely to use the Internet as a crutch, the nonlonely as a leverage. “So,” Cacioppo says, “the rich get richer and the poor get poorer.”


One way to stem rising loneliness on a large scale may be to build what Cacioppo calls “social resilience”: communities whose structure or makeup fosters social well-being and whose cohesion is strong enough to weather misfortune. “If what I’m saying is true, if loneliness in part gives us the capacity to sculpt a better species,” Cacioppo says, “then how can we put together better groups, better towns, better communities, better societies?”

Last December he and researchers from Harvard and the University of California, San Diego, published a paper suggesting loneliness is contagious. Using data from a longitudinal study in small-town Framingham, Massachusetts, they charted a social network of more than 12,000 ties among 5,124 people, determining that having one lonely friend raised one’s chance of loneliness by 40 to 65 percent. A lonely friend-of-a-friend raised the chance by 14 to 36 percent. By the third degree of separation, the increased likelihood was slighter still, and beyond that the effect disappeared. The phenomenon makes sense to Cacioppo. “When I’m lonely, I’m more likely to interact with other people negatively,” he says. That bad feeling spreads. “Think about it: you have a bad day at work, you go home, your spouse suffers. Well, so do strangers and friends you interact with.”

That study helped inform a new project. Working with sociologists, Cacioppo is constructing a spatial map of Chicago’s South Side, in which each of the 82 neighborhoods is broken down into areas where higher percentages of people feel more and less lonely. The next task is to figure out what makes the lonely areas so. “It’s not socioeconomic status,” Cacioppo says. He’s looking at neighborhood features such as block parties, well-kept homes, clean streets, public facilities, and crime. How much difference does a community center make? What about flower boxes along the sidewalks?

An even more elusive and delicate task is figuring out how to solve individuals’ persistent loneliness. In August Cacioppo; Medical Center researcher Christopher Masi, PhD’01; and two other coauthors published a sweeping analysis of every study on loneliness intervention done between 1970 and September 2009. Treatments fell into four types: fostering “social contact” by bringing lonely people together or providing access to e-mail; offering “social support” from visitors or dogs or group activities; teaching social skills; and changing the way they think about themselves and other people. Of those, the last, training in “social cognition”—the ability to understand and navigate social interactions—yielded promising results.

Meanwhile, the e-mails from readers persist, some offering stories of hope, emergence. Cacioppo opened one section of Loneliness with a note from a Florida woman: “I made a resolution last year to make more eye contact with people and say hello to strangers every day. I am surprised by their reaction. It is very uplifting for me and I hope for them.” In the book, Cacioppo laid out general recommendations for fighting loneliness; he and a clinical psychologist are working to shape them into a course of cognitive behavior therapy. He advised readers to reach out, even in small ways, to those around them, to volunteer, say hello to someone at the grocery store or the library, and eventually to find compatible, fulfilling friends. To open their lives.

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