Categories
Life Style

Why loneliness is bad for your health

[ad_1]

In 2010, Theresa Chaklos was diagnosed with chronic lymphocytic leukaemia — the first in a series of ailments that she has had to deal with since. She’d always been an independent person, living alone and supporting herself as a family-law facilitator in the Washington DC court system. But after illness hit, her independence turned into loneliness.

Loneliness, in turn, exacerbated Chaklos’s physical condition. “I dropped 15 pounds in less than a week because I wasn’t eating,” she says. “I was so miserable, I just would not get up.” Fortunately a co-worker convinced her to ask her friends to help out, and her mood began to lift. “It’s a great feeling” to know that other people are willing to show up, she says.

Many people can’t break out of a bout of loneliness so easily. And when acute loneliness becomes chronic, the health effects can be far-reaching. Chronic loneliness can be as detrimental as obesity, physical inactivity and smoking according to a report by Vivek Murthy, the US surgeon general. Depression, dementia, cardiovascular disease1 and even early death2 have all been linked to the condition. Worldwide, around one-quarter of adults feel very or fairly lonely, according to a 2023 poll conducted by the social-media firm Meta, the polling company Gallup and a group of academic advisers (see go.nature.com/48xhu3p). That same year, the World Health Organization launched a campaign to address loneliness, which it called a “pressing health threat”.

But why does feeling alone lead to poor health? Over the past few years, scientists have begun to reveal the neural mechanisms that cause the human body to unravel when social needs go unmet. The field “seems to be expanding quite significantly”, says cognitive neuroscientist Nathan Spreng at McGill University in Montreal, Canada. And although the picture is far from complete, early results suggest that loneliness might alter many aspects of the brain, from its volume to the connections between neurons.

Subjective and contagious

Loneliness is a slippery concept. It’s not the same as social isolation, which occurs when someone has few meaningful social relationships, although “they’re two sides of the same coin”, says old-age psychiatrist Andrew Sommerlad at University College London. Rather, loneliness is a person’s subjective experience of being unsatisfied with their social relationships.

The list of health conditions linked to loneliness is long and sobering1 (see ‘Loneliness and health’). Some of these make intuitive sense — people who feel lonely are often depressed, for example, sometimes to the point of being at risk of suicide. Other links are more surprising. Lonely people are at greater risk of high blood pressure and immune-system dysfunction compared with those who do not feel lonely, for example. There’s also a startling connection between loneliness and dementia, with one study reporting that people who feel lonely are 1.64 times more likely to develop this type of neurodegeneration than are those who do not3.

LONELINESS AND HEALTH. Graphic shows lonely adults are more likely to be diagnosed with a range of physical health issues.

Source: The Cigna Group

A number of physiological effects, including the ability to sleep, increased stress-hormone levels and increased susceptibility to infections, could link loneliness with health problems. But the way in which these factors interact with one another makes it difficult to disentangle the effects of loneliness from the causes, cautions cognitive neuroscientist Livia Tomova at Cardiff University, UK. Do people’s brains start functioning differently when they become lonely, or do some people have differences in their brains that make them prone to loneliness? “We don’t really know which one is true,” she says.

Whatever the cause, loneliness seems to have the biggest effect on people who are in disadvantaged groups. In the United States, Black and Hispanic adults, as well as people who earn less than US$50,000 per year, have higher rates of loneliness than do other demographic groups by at least 10 percentage points, according to a 2021 survey by the Cigna Group, a US health-care and insurance company (see go.nature.com/43eakds). That’s not surprising because “loneliness, by definition, is an emotional distress that wants us to adapt our social situations”, says geriatrician and palliative-care physician Ashwin Kotwal at the University of California, San Francisco. Without financial resources, adapting is harder.

The COVID-19 pandemic might have exacerbated loneliness by forcing people to isolate for months or years, although “that data is still emerging”, Kotwal says. Older adults have long been thought of as the demographic most heavily affected by loneliness, and indeed it is a major problem faced by many of the older people that Kotwal works with. But the Cigna Group’s data suggest that loneliness is actually highest in young adults — 79% of those between the ages of 18 and 24 reported feeling lonely, compared with 41% of people aged 66 and older.

Loneliness eats at you

A growing amount of research is exploring what happens in the brain when people feel lonely. Lonely people tend to view the world differently from those who aren’t, says cognitive neuroscientist Laetitia Mwilambwe-Tshilobo at Princeton University in New Jersey. In a 2023 study, researchers asked participants to watch videos of people in a variety of situations — for example, playing sports or on a date — while inside an magnetic resonance imaging scanner4. People who did not report being lonely all had similar neural responses to each other, whereas the responses in people who felt lonely were all different — from the other group and from each other. The authors hypothesized that lonely people pay attention to different aspects of situations from non-lonely people, which causes those who feel lonely to perceive themselves as being different from their peers.

This would mean that loneliness can feed back on itself, becoming worse over time. “It’s almost like a self-fulfilling prophecy,” Mwilambwe-Tshilobo says. “If you think that you’re lonely, you’re perceiving or interpreting your social world more negatively. And that makes you move further and further away.” Some studies have shown that this effect can spread through social networks, giving loneliness a contagious quality5.

Historically, staying close to others was probably a good survival strategy for humans. That’s why scientists think that temporary loneliness evolved — to motivate people to seek company, just as hunger and thirst evolved to motivate people to seek food and water.

In fact, the similarities between hunger and loneliness go right down to the physiological level. In a 2020 study, researchers deprived people of either food or social connections for ten hours. They then used brain imaging to identify areas that were activated by images of either food — such as a heaping plate of pasta — or social interactions, such as friends laughing together. Some of the activated regions were unique to images either of food or of people socializing, but a region in the midbrain known as the substantia nigra lit up when hungry people saw pictures of food and when people who felt lonely saw pictures of social interactions6. That’s “a key region for motivation — it’s known to be active whenever we want something”, says Tomova, who is an author on the study.

More links are emerging between loneliness and how the brain processes feelings of reward. In mice, loneliness sensitizes certain midbrain neurons to a neurotransmitter called dopamine7, which can also cause people to cave in to cravings, such as for food and drugs. Likewise, isolation might make humans more sensitive to rewards and more eager to seek them out. In 2023, Tomova and her colleagues published a preprint8 for a study in which they isolated adolescents from social contact for up to four hours. After isolation, participants were offered the chance to earn a monetary reward. The isolated participants agreed more quickly than did those who were not isolated, suggesting that isolation had made them more responsive to rewarding actions.

Although research on dopamine and loneliness is still emerging, scientists have also long recognized the connection between loneliness and another type of chemical signal — stress hormones called glucocorticoids. Humans need some level of glucocorticoids “to function; to wake up”, says neurophysiologist John-Ioannis Sotiropoulos at the National Centre for Scientific Research ‘Demokritos’ in Athens. But persistent loneliness leads to chronically high levels.

These chemicals could provide a link between loneliness and dementia. In a mouse model of Alzheimer’s disease, for example, glucocorticoids increased the levels of two proteins that are involved in the main hallmark of the condition, the protein plaques that tangle around neurons and interfere with memory and cognition9.

Stress is an extra assault on brains that are already wearing out as people get older, Mwilambwe-Tshilobo says, but she wants to see more research before committing to an opinion on exactly what part stress-related chemicals play in neurodegeneration. “It could accelerate the rate of ageing, but there hasn’t been work that explicitly looks at that,” she says.

Tomova says that although high levels of stress hormones probably contribute to dementia, it’s also likely that people who feel lonely miss out on the mental exercise that social interactions provide. And just as a muscle needs exercise to stay fit, so does the brain. In fact, loneliness has been associated with a smaller volume of grey matter in the brain10. “This is all hypothesis, really, at this stage,” Sommerlad says, but the idea is that socializing maintains neural connections that might otherwise be lost.

Turning inward

Researchers looking for the neural signature of loneliness have also found differences that could help to explain some of the correlations between loneliness and dementia. Previous research has suggested that there are changes in the connectivity between brain areas in people who feel lonely11. A 2020 study12 examined an area of the brain called the default network — so called because it’s active by default when a person isn’t engaged in a particular task and turns their attention inward — in older people who reported being lonely.

Previous work had suggested that young people who feel lonely have high neural cross-talk between the default network and other networks associated with vision, attention and executive control13, possibly because they’re on high alert for social cues, says Spreng, one of the authors on the 2020 study of older people. But his team found the opposite in brain scans from the UK Biobank cohort of people aged 40 to 69. Loneliness weakened connections between the default network and the visual system and instead strengthened connections within the default network.

That could be because older people remedy loneliness by retreating into memories of past social experiences, Spreng says. In doing so, they strengthen the default network.

The default network is one of many networks in the brain that accrues damage during Alzheimer’s disease. Spreng and his colleagues are investigating whether strong default networks can indeed be linked to neurodegeneration — and if so, why. He wonders whether robust neural connections might allow pathologies to spread more readily in the network. The idea is far from proven, but it’s a plausible explanation and “an interesting hypothesis”, says cognitive neuroscientist Anastasia Benedyk at the Central Institute of Mental Health in Mannheim, Germany.

The study “lays the foundation for us to be able to test some hypotheses a little bit more empirically”, says Mwilambwe-Tshilobo, who was also involved in the work linking the default network with loneliness.

Finding solutions

Some remedies for loneliness will come as no surprise. Increasing access to social activities, for example by housing people in communities with common areas, can help, Sommerlad says. Some researchers are also finding ways to tap into the neural mechanisms underlying loneliness directly, through exercise, for instance.

Walking 4–5 kilometres over the course of an hour completely reversed feelings of low mood associated with loneliness in some people, Benedyk and her colleagues found14. What’s more, people with high connectivity in their default networks — the same area Spreng studied, which is also known to be affected by depression — were among those who benefited from exercise the most.

One possible explanation for this observation is that people with depression are “stuck in rumination” — a behaviour that draws heavily on the default network, Benedyk says. Exercise could force them to use other parts of their brain by interrupting neural processes that are associated with self-reflection and shifting activity to areas associated with physical activities — freeing them from a cycle of negative thoughts.

Exercising is also a great excuse to socialize. These days, Chaklos is retired, but she now leads the Boston branch of a US programme called ‘Walk with a Doc’, in which physicians invite community members to walk with them. At the group’s February walk, about 14 people chatted and strolled inside the Prudential Center mall in Boston, Massachusetts, where they could avoid New England’s winter weather. The activity “just uplifts a person’s mood”, Chaklos says. “Even if you’re still going back home to be by yourself, you don’t feel totally alone any more.”

[ad_2]

Source Article Link

Categories
Life Style

159 days of solitude: how loneliness haunts astronauts

[ad_1]

Cady Coleman looking out of the Soyuz.

In 2010, astronaut Cady Coleman left her husband and young son to go into space.Credit: NASA/Bill Ingalls

Space: The Longest Goodbye Greenwich Entertainment Directed by Ido Mizrahy

Neither NASA nor the Chinese space agency are probably consulting screenwriters as they develop their plans to send humans to the Moon and Mars. But they need to take the problem of astronaut isolation seriously, as director Ido Mizrahy sets out in his heartfelt documentary Space: The Longest Goodbye. Released in cinemas and online this week, this thoughtful film shares first-hand accounts of how leaving family behind can wreak havoc on an astronaut’s well-being.

Any crewed trip to Mars, for example, will involve up to three years of spaceflight — a sea change in what humans have experienced so far. Russian cosmonaut Valery Polyakov holds the record for the longest-duration spaceflight: 437 consecutive days aboard the Mir space station from January 1994 to March 1995. He and other cosmonauts pioneered the study of how the human body responds to microgravity over time, from bone deterioration to muscle loss and vision changes.

Yet the psychological impacts of spaceflight are equally important, argues Al Holland, an operational psychologist at the NASA Johnson Space Center in Houston, Texas, who drives much of the narrative for The Longest Goodbye. He and his colleagues studied NASA astronauts who flew on Mir, and used the lessons to try to improve astronauts’ mental health and well-being on board the International Space Station (ISS) during the 1990s. For example, carrying mechanical spare parts on board, which weren’t always stowed on Mir, reduced stress levels because astronauts knew that they had backups in case of an emergency.

Easing mental strain

Holland’s team developed ways to lessen the psychological strain of separation, such as by providing twice-weekly audio- or videoconferences between astronauts aboard the ISS and their families, and phone calls home whenever needed. The Longest Goodbye explores these long-distance conversations poignantly, through video recordings shared by Cady Coleman, a NASA astronaut who spent 159 days aboard the ISS in 2010–11.

As Coleman speaks with her husband and ten-year-old son from orbit, they mimic her, drifting across the screen as they pretend to float in microgravity. In another call, Coleman and her son play a flute duet. But after being separated from his mum for so long, he begins to act up. As she reads a story to him, he gets off the couch and makes faces at the camera. He is often like this just before joining calls with Coleman, her husband tells her. From her screen, Coleman can’t do much more than raise her eyebrows sternly.

Cady and son speaking while she's on the space station.

Coleman had frequent videoconferences with her son, but her absence was still hard on both of them.Credit: Cady Coleman

The video connection breaks up -repeatedly. Coleman cries on camera — a lot. In recent interviews for the film, her son talks about how he didn’t understand why she had to be gone for so long. It is a heartbreaking glimpse into the personal challenges of one of NASA’s most accomplished astronauts, and a warning for anyone thinking about taking a three-year trip to Mars. Being separated from your family for a long journey on Earth is challenging enough; being apart while enduring the unique stresses and dangers of spaceflight is much harder.

The film illuminates this while following the story of Kayla Barron, a NASA astronaut who flew aboard the ISS from November 2021 to May 2022. Barron is a former submariner who has experienced stressful military deployments, but says that going to space is very different. Just getting to orbit in the first place involves putting yourself atop a flaming rocket, she notes. “It’s the most dangerous thing you’ve ever done, and then you invite all of your family and friends to come watch it.” “My spouse is on top of this ball of fire,” her husband thinks.

The couple confronts the existential -question of whether, if she dies, she is doing what she wanted to be doing. In one scene, she rushes to shelter in a protected part of the ISS as an errant piece of space debris threatens to hit the station. Her husband sits helplessly at home, frantically trying to get updates.

Might spacefarers find other ways to -recreate human bonds? European Space Agency astronaut Matthias Maurer, who was on the ISS at the same time as Barron, is shown interacting with an artificial-intelligence assistant. It looks like a floating football and has a screen with a creepily simplified human face. Viewers are likely to be relieved when Maurer packs it away in its storage case.

Lessons on Earth

The film also recaps the rescue of 33 -Chilean miners in 2010, who had been trapped during a mine collapse and spent 69 days underground. Holland and other NASA employees advised the Chilean government on how to sustain the miners’ physical and psychological well-being during their extended isolation. They were told to eat and sleep on a strict schedule, and set up an illuminated area so they could transition between ‘day’ and ‘night’ while they awaited rescue. Lessons from space thus helped the miners to survive underground.

The Longest Goodbye doesn’t describe what might work best for astronauts on their way to Mars. But it does offer a poignant look at the isolation and loss of connection that so many astronauts feel in space, and that many of the rest of us might recognize a little from our own experiences during the COVID-19 pandemic.

Competing Interests

The author declares no competing interests.

[ad_2]

Source Article Link