Carrie Aulenbacher grew up painfully lonely in rural Pennsylvania. Despite having a loving husband and friends, the 39-year-old administrative assistant and writer in Erie still battles her sense of aloneness.

In high school, she had feared approaching a group of girls. She felt she would not know what to say—and maybe they would turn on her. She constantly questions and judges herself. “Am I purposely making myself lonely by projecting things I don't realize?” she asks. “Am I trying so hard I'm pushing people away?”

Over the years Aulenbacher has grown and changed in many ways, but the loneliness remains. Recently she spoke at a seminar. “I arrived alone. I went to lunch alone,” she reports. “No one invited me, and I didn't try to belong. Should I have? Yes.”

“You learn to move through the world and reach out,” she says through tears, “but loneliness stinks.”

Loneliness like Aulenbacher's, which may seem to be the ordinary stuff of life and literature, has been attracting a torrent of scientific inquiry. From psychology to epidemiology to evolutionary biology, researchers have been probing the nature of different types of loneliness, their biological mechanisms and their effects on mind and body.

Growing evidence has linked loneliness to a marked vulnerability to a host of psychological and physiological ills, from depression and cognitive decline to heart problems and stroke. A 2015 meta-analysis (combining studies between 1980 and 2014) by psychologist Julianne Holt-Lunstad of Brigham Young University and her colleagues found that loneliness, social isolation and living alone—even more so than obesity—were all associated with a higher chance of early death. Reviewing the available evidence in 2017, Holt-Lunstad and her colleagues concluded that insufficient social connection, stemming not only from feelings of loneliness but also from isolation and poor-quality relationships, is a major public health concern.

How lonely are we exactly? Some scholars such as Holt-Lunstad cite indicators that social isolation, which can cause loneliness, is rising: more individuals living alone, falling marriage rates, fewer children, declining volunteerism and fewer Americans reporting a religious affiliation. In a 2006 study by researchers at Duke University and the University of Arizona, the number of Americans who said they had no close confidants tripled from 1985 to 2004. But other statistics depict a different picture. The subjective feelings of loneliness among adults, says sociologist Keming Yang of Durham University in England, who has analyzed European data from 2006 to 2014, are “quite stable” at about 7 to 10 percent. For the U.K., he says, it “is pretty stable at 5 to 6 percent.”

Whether or not loneliness is growing—and that depends partly on what is being measured—the link to health problems has awakened a desire worldwide to find ways to reduce it. In 2011 Crown Princess Mary of Denmark launched a national effort to diminish loneliness. In the U.S., AARP is funding several loneliness-reduction efforts for older people. Age UK, a group similar to AARP, and other organizations unleashed the Campaign to End Loneliness in 2011, researching interventions for loneliness. In 2016 the BBC documentary The Age of Loneliness trumpeted the “loneliness epidemic” and helped to make the topic a national priority. “The message has gone out,” says Brunel University London gerontologist Christina Victor. “If only you'd all go round and visit your granny, she wouldn't have to go to hospital.”

What is it Exactly?

We have all felt “lonely” at some point, but for most of us, that feeling depends on our situation and how we look at it. Loneliness is defined as perceived social isolation and the experience of being cut off from others. Among the majority of sufferers, it can change as our status shifts: when finding new friends, for example, or perhaps beginning a new romantic relationship. People whom researchers define as “chronically lonely” experience profound loneliness over long periods, despite changing circumstances.

What they feel is not the same as depression, social anxiety or shyness, although these conditions often overlap with chronic loneliness. According to psychologist Ken Rotenberg of Keele University in England, studies show that chronically lonely people are more likely than others to show dysfunctional styles of processing social information (hypervigilance for social threats), psychological problems (depression) and interpersonal maladjustment (social withdrawal).

Social isolation, which can cause loneliness, can be measured objectively by factors such as living alone and having few affiliations or neighbors. Some who are socially isolated may feel perfectly content. Others who are not at all isolated by objective standards—consider a married person with many friends—may feel profoundly lonely. Both loneliness and social isolation have been correlated with heightened health risks, albeit probably for different reasons. Loneliness may also be associated with physiological responses that affect health. For socially isolated people who do not feel lonely, Holt-Lunstad says, “there may be no one to remind you to take your medicine, no one to call 911.”

The data on how many people experience both social isolation and loneliness and whether this subgroup faces the greatest risk are complex. The overlap is hard to pin down.

Part of the problem in the scientific literature is that the standard tools for measuring loneliness do not necessarily gauge the same things. Often used in large European surveys, the De Jong Gierveld Loneliness Scale measures both loneliness and social isolation but not their duration. It simply asks people to answer “yes!” “yes,” “more or less,” “no” and “no!” to such statements as “I miss having a really close friend” and “There are many people I can trust completely.”

The most commonly used measure of loneliness, the Revised UCLA Loneliness Scale, assesses individuals' perceived dissatisfaction with the quality or quantity of their relationships. People rate, for example, how often they feel close to others, lack companionship, or feel shy or alone. The measures are primarily cognitive—examining self-perception and other factors rather than delving into the actual feeling of loneliness. For some, Rotenberg says, “the emotional experience of loneliness, when your gut is in a knot, can be quite brutal and undermine mental health if it persists.”

Classic Research

Since the mid-20th century psychologists have focused on loneliness as separate from depression or other psychic ills—often proposing theories that have since been left aside. In a 1959 article entitled “Loneliness,” German psychoanalyst Frieda Fromm-Reichmann referred to its “naked horror” and theorized that it arose from premature weaning. In the 1970s and 1980s, as research intensified, some scholars hypothesized that the primary cause was not being fully part of an accepting social network or community. Others focused on cognition, the negative and unrealistic way that lonely people see themselves and others.

University of Chicago neuroscientist John Cacioppo has more recently proposed an influential theory, positing that loneliness serves an evolutionary function. When people see themselves as excluded from a social group, they feel less safe from threats—individuals perceived as enemies, for instance.

Source: “Age Differences in Loneliness from Late Adolescence to Oldest Old Age,” by Maike Luhmann and Louse C. Hawkley, in Developmental Psychology, Vol. 52, No. 6; June 2016

In Cacioppo's evolutionary theory, the pain of loneliness triggers both a motivation to connect to others, known as the reaffiliation motive (RAM), and a hypervigilance to social threats, along with neural changes that increase physical stress. These traits are not unique to humans and function as a survival mechanism.

In everyday life, explains psychologist Pamela Qualter of the University of Central Lancashire in England, people will become quiet or withdraw as a way of observing the social world and will try to work out ways to reconnect. “Let's say I'm at a party,” she says, “and I don't know anyone well. I'm feeling unsure and lonely. I'd observe [the situation] and try to identify people I might connect with and people I might want to avoid.”

Stephanie Cacioppo, a University of Chicago neuroscientist who researches loneliness with her husband, John Cacioppo, explains that people will find a way to connect, and the adjustments triggered by loneliness are reversed. But when efforts to repair or form new social connections repeatedly fail, people may stay in a hyperalert mode that stresses the body and brain. Such a person's mind, Stephanie Cacioppo says, is always on the lookout, searching for threats before they face harm. But this response is often counterproductive because of the difficulty of differentiating a real threat from an ambiguous social cue.

How Lonely?

People tend to be more vulnerable to loneliness, it turns out, at certain times of life—and this understanding has focused research. Increasingly, scientists are looking at two age groups of the lonely: the young (under 30) and the old (over 60).

The need to channel efforts at both ends of the age spectrum emerges from various findings. In looking at 2,393 British subjects aged 15 to 97, Brunel's Victor and Durham's Yang reported in 2012 that the highest levels of loneliness occurred before age 25 and after age 65. Similarly, a large German population study published in 2016 by psychologists Maike Luhmann, then at the University of Cologne in Germany, and Louise C. Hawkley of the University of Chicago found that the loneliest groups were younger than 30 and older than 80 [see graph above].

These reports of people's feelings, Luhmann and Hawkley speculate, are influenced by what is perceived as “normal” at each life stage. Study after study, for example, has found that being married or cohabiting protects against loneliness, but that factor may have less impact on young people who do not yet expect to be married and may be less critical to the very old, for whom widowhood is common. Being employed can make a crucial difference for adults in midlife but less so for older people who have chosen to retire. Meanwhile certain fairly predictable factors—social engagement, number of friends and frequency of contacts—appear to be universal predictors of loneliness at any age.

Why are Children Lonely?

A major emphasis of research spotlights children and adolescents because of the lingering effect that loneliness can have throughout a lifetime. Studies have shown that it can lead to depression, and lonely children are at an increased risk of becoming lonely and depressed adolescents and adults. A 2010 British study of nearly 300 children ages five to 13 found that lonely children were likelier to be depressed as adolescents.

Some children in the study were lonely in relationships with their parents, others in relationships with their peers. The work of Marlies Maes of KU Leuven in Belgium and her colleagues shows that adolescents who felt lonely with their peers but not with their parents were seen as more shy and were likelier to be identified as victims of bullying.

Some kids are lonely because they have inadequate social skills. In a 2016 study, 1,342 adolescents rated themselves and their classmates on how well they dealt with others. By comparing the subjects' self-evaluations with those of their classmates, says lead author and behavioral scientist Gerine M. A. Lodder of the University of Groningen in the Netherlands, the researchers found that lonely children fell into two groups. The ones whose classmates agreed that they had poor social skills very likely did, but they might still be capable of change. Relationships entail different social tasks, says Duke developmental psychologist Steven R. Asher. They include taking the initiative to make social contacts, being a reliable partner and resolving conflicts. Although some children are worse than others at handling these tasks, kids can potentially learn to improve their interactions and become less lonely.

The other group in Lodder's study had a pervasive negative view of themselves, their social environment and their social relations—and at times might need a different approach. “There is no one-size-fits-all solution,” Lodder says.

Many intensely lonely kids have fine social skills. Qualter has observed a group of children ranging from ages eight through 14 in their dealings on the playground and in other interactions. The loneliest of them, she says, behave much like other children but interpret their interactions differently.

She has found the same with college students. With a best friend, lonely students appear to behave just like everyone else. But afterward, Qualter explains, they say, “I talk too much” or “too little.” On average, they underestimate their performance.

Findings from these studies with children and adolescents fit with John Cacioppo's model of faulty RAM and intense hypervigilance. The research indicates that severely lonely children and young adults respond differently to images and situations of social inclusion and exclusion.

A 2015 study of 730 adolescents by developmental psychologist Janne Vanhalst of KU Leuven and her colleagues suggested that chronically lonely adolescents may stay lonely because of their negative interpretations of social situations. Testing them annually over four years, the investigators found that those who stayed lonely responded more negatively to scenarios describing social exclusion, such as not being invited to a new lunch place. Strikingly, they also responded less enthusiastically to scenarios describing being included, such as being invited to a party. They were more likely to attribute the invitation to coincidence than to being likable. “Not taking as much pleasure in being included, as well as getting more upset about being excluded, is a kind of double whammy,” says Asher, a co-author of the study.

One idea in the search for the roots of loneliness in the young holds that low trust issues cause or maintain loneliness. In 2010 studies by Rotenberg and his colleagues of children in age groups of five to seven, nine to 11, and 18 to 21 who had diminished trust exhibited increases in loneliness in each age group over time.

In one of the studies, the researchers asked young adults to learn a series of “trusting” or “distrusting” words (“loyal” versus “dishonest,” for example) before having an interaction with another person that was carefully structured by the researchers. Those “primed” for trust were likelier to pick more intimate topics to discuss and to report that they “hit it off” with the other person.

Different in the Old

Do all the lessons from studying young people apply to later life? Probably not. The elderly are not in fact really lonely, says Victor, who has done stereotype-busting research on the old. Yet, she says, “in Britain, it's seen as normal for aging people to be lonely.”

In a study conducted in 2000 and 2008 with almost 1,000 people older than 65, she and her colleague found that 9 percent reported severe loneliness. Of the individuals in the study, 30 percent said they were sometimes lonely, and an impressive 61 percent reported they were never lonely. Greater levels of loneliness, Victor notes, were linked to life changes: losing a partner or having impaired physical health. Victor and her colleague also found, in a 2015 study, that contrary to popular belief, the loneliest time for older people was not Christmas but summer, when family routines change. She says she had thought of calling the study “No One Invites Granny to the Beach.”

Solitude Reduction

As the scientific consensus has grown that loneliness and social isolation are linked to physical and emotional decline, researchers have tested an array of remedies. In 2011 internist Christopher Masi, then working with John Cacioppo at Chicago and now at NorthShore University HealthSystem and other researchers, analyzed 20 well-designed loneliness interventions out of a total of 50 studies published between 1970 and 2009. They fell into four main categories: improving lonely people's social skills, increasing social support, encouraging interactions with other people, and providing cognitive-behavioral therapy (CBT), a form of talk therapy that tries to dispel or reframe negative interpretations of an individual's experiences. “On average,” Masi says, “for all 20, the overall effect was reducing loneliness.” But the intervention that really stood out, he reports, was CBT.

Given that lonely children become lonely (and depressed) adolescents and adults, you might think that scientists would be focusing their intervention efforts on the youngest sufferers. Alas, Groningen's Lodder says, “for kids, there's not much out there.”

The barriers to helping children are clear to Ami Rokach, a clinical psychologist who teaches at York University in Toronto. In his private practice, he treats chronically lonely adults using CBT. For teenagers as young as 16, he uses a variety of approaches, and CBT is frequently one part of the therapy. “CBT works for them,” he says, “if I can get their parents onboard. It's very difficult if they go home and get the message that they're unlikable or that you can't trust people.”

The other end of the age spectrum has witnessed a burst of innovation. Mindfulness training, robot pets and teaching the elderly how to use Skype have all been tried. Pairing elderly people with similar-aged volunteers for a series of visits, reports Trinity College Dublin psychiatrist Brian Lawlor, showed some effectiveness in reducing loneliness. But interventions that include CBT have shown more impressive gains.

A 2016 study by West Virginia University gerontological nursing professor Laurie Theeke and her colleagues, for example, demonstrated the effectiveness of CBT. The 27 lonely volunteers (screened with the full UCLA scale) received either five weeks of a structured group therapy program called LISTEN or heard lectures on healthy aging.

The therapy groups, made up of three to five older men and women, discussed and wrote about such topics as “belonging” or “relationships.” They learned to revise some of their negative assumptions. An 83-year-old retired executive who had felt useless heard from the others that his skills as a businessperson could still be used; afterward, he created a newsletter for seniors in his building. A 65-year-old woman who felt no man would enjoy her company heard from men in her group that they did like being with her.

Twelve weeks after the program the LISTEN participants had reduced loneliness levels—“almost to the nonlonely range,” Theeke says—and they also experienced enhanced social support and decreased systolic blood pressure. The control group reported decreased functional ability and quality of life.

The LISTEN participants admitted, both to themselves and to others, that they were lonely. Not all lonely people can do this. Some of the best interventions, Victor says, do not tackle loneliness head on but the underlying circumstances. If people's health keeps them indoors, she suggests, walking groups should be created. If they lack transit, it should be provided. She recalls a shopping service her mother used that took a group of elderly women to the market weekly. They began exchanging phone numbers and making friends. “They would not have dreamed of talking to one another in the street,” Victor says.

Many people, experts say, worry that if they acknowledge being lonely, others will think there is something wrong with them. Public campaigns to bring loneliness to the attention of others may help, so may exploding myths about loneliness, especially for older people.

The myth that it is typical for old people to be lonely, Victor says, can itself be harmful. In 2016 she and her colleagues reported on a study of people older than 50. When initially tested, those who expected to be lonely were in fact likelier to be lonely eight years later than those who did not.

The Future of Loneliness Research

The more scientists learn about loneliness, the better they are able to identify groups at risk because of specific issues. A 2016 Danish population-based study by psychologist Mathias Lasgaard of DEFACTUM and the University of Southern Denmark and his colleagues, for example, identified certain high-risk groups, including those who are ethnic minorities, unemployed, on disability, suffering from a long-term mental illness and living alone. Interventions might be developed specifically for these groups.

For chronically lonely people, CBT remains the treatment of choice, but drug therapy with allopregnanolone, a neurosteroid, is showing promise in animal studies in reducing perceived social isolation and may eventually become a useful adjunct to CBT, Chicago's Stephanie Cacioppo says. New approaches for the loneliness of the old continue to proliferate.

The biggest challenge is alleviating the plight of chronically lonely children. It may be eventually possible to craft interventions, York's Rokach says. “It is doable, but it takes work and dedication by both teachers and parents. Many are not enlightened. They tell the kids, ‘Just go out and play.’”