Lonely people's divergent thought processes may contribute to feeling 'alone in a crowded room'

Common wisdom suggests that a core difference between solitude and loneliness is choice. Whereas a person who appreciates solitude might choose to enjoy a quiet night in or a solo trip abroad, a lonely person may feel disconnected from other people even in a crowded room. New research published in Psychological Science supports this notion, suggesting that lonely people may think differently regardless of the size of their social networks.

"We found that lonely individuals are exceptionally dissimilar to their peers in the way that they process the world around them … even when taking into account the number of friends that they have," said lead author Elisa C. Baek (University of Southern California) in an interview. Her study showed that lonely individuals' neural responses differ from those of other people, suggesting that "seeing the world differently than those around you may be a risk factor for loneliness, even if you regularly socialize with them."

Baek and colleagues Ryan Hyon, Karina López, Meng Du, Mason A. Porter, and Carolyn Parkinson (University of California, Los Angeles [UCLA]) came to this conclusion by comparing the functional magnetic resonance imaging (fMRI) scans of 63 first-year university students.

During each 90-minute scan, participants viewed 14 engaging video clips in the same order. After the scan, they self-reported their feelings of social connection using the UCLA Loneliness Scale. Earlier in the academic year, each participant had also completed a social network survey in which they were asked to list the names of each person with whom they studied, ate meals, or otherwise hung out during their first several months as students.

In order to analyze these data, Baek and colleagues divided participants into two groups: a "lonely" group with participants who scored higher than the median on the loneliness scale and a nonlonely group with participants who scored under the median.

When the researchers compared these participants' scans, they found that the brain activity of lonely participants was very dissimilar to that of both nonlonely participants and other lonely participants. By comparison, the brain activity of nonlonely participants was similar to that of other nonlonely participants. This was especially true in the default-mode network, in which shared brain activity appears to be associated with interpreting narratives and friendships in a similar manner, and in the reward-processing areas of the brain, the researchers wrote. These findings remained significant even when the researchers controlled for demographic characteristics and the size of participants' social networks.

"Lonely people process the world idiosyncratically, which may contribute to the reduced sense of being understood that often accompanies loneliness," the researchers explained.

Additional research is needed in order to determine the underlying cause of these results, however, Baek said.

"One possibility is that lonely individuals do not find value in the same aspects of situations or scenes as their peers," Baek and colleagues wrote. "This may result in a reinforcing feedback loop in which lonely individuals perceive themselves to be different from their peers, which may in turn lead to further challenges in achieving social connection."

Another possibility is that loneliness itself could lead people to process information differently, the researchers added.

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Loneliness leads to higher risk of future unemployment

Experiencing loneliness appears to lead to a higher risk of future unemployment, according to new research.

Previous research has established that being unemployed can cause loneliness, however the new study from the University of Exeter is the first to directly explore whether the opposite also applies across the working age population. Published in BMC Public Health, the study found that people who reported "feeling lonely often" were significantly more likely to encounter unemployment later. Their analysis also confirmed previous findings that the reverse is true -- people who were unemployed were more likely to experience loneliness later.

Lead author Nia Morrish, of the University of Exeter, said: "Given the persisting and potentially scarring effects of both loneliness and unemployment on health and the economy, prevention of both experiences is key. Decreased loneliness could mitigate unemployment, and employment abate loneliness, which may in turn relate positively to other factors including health and quality of life. Thus, particular attention should be paid to loneliness with additional support from employers and government to improve health and wellbeing. Our research was largely conducted pre-pandemic, however we suspect this issue may be even more pressing, with more people working from home and potentially experiencing isolation because of anxieties around covid."

The research analysed largely pre-pandemic data from more than 15,000 people in the Understanding Society Household Longitudinal Study. The team analysed responses from the participants during 2017-2019, then from 2018-2020, controlling for factors including age, gender, ethnicity, education, marital status, household composition, number of own children in household and region.

Senior author Professor Antonieta Medina-Lara said: "Loneliness is an incredibly important societal problem, which is often thought about in terms of the impact on mental health and wellbeing only. Our findings indicate that there may also be wider implications, which could have negative impacts for individuals and the economy. We need to explore this further, and it could lay the foundations for employers or policy makers to tackle loneliness with a view to keeping more people in work."

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Lonely flies, like many humans, eat more and sleep less

COVID-19 lockdowns scrambled sleep schedules and stretched waistlines. One culprit may be social isolation itself. Scientists have found that lone fruit flies quarantined in test tubes sleep too little and eat too much after only about one week of social isolation, according to a new study published in Nature. The findings, which describe how chronic separation from the group leads to changes in gene expression, neural activity, and behavior in flies, provide one of the first robust animal models for studying the body's biological reaction to loneliness.

"Flies are wired to have a specific response to social isolation," says Michael W. Young, the Richard and Jeanne Fisher Professor and head of the Laboratory of Genetics at Rockefeller. "We found that loneliness has pathological consequences, connected to changes in a small group of neurons, and we've begun to understand what those neurons are doing."

The science of loneliness

Drosophila are social creatures. The fruit flies forage and feed in groups, serenade one another through complex mating rituals, tussle in miniature boxing matches. And then they conk out: flies sleep 16 hours each day, split between a languorous midday nap and a full night's rest.

So when Wanhe Li, a research associate in Young's lab, began investigating the biological underpinnings of chronic social isolation, she turned to the gregarious and well-studied fruit fly. "Over and over again, Drosophila have put us on the right track," says Young. "Evolution packed a great deal of complexity into these insects long ago and, when we dig into their systems, we often find the rudiments of something that is also manifest in mammals and humans."

"When we have no roadmap, the fruit fly becomes our roadmap," Li adds.

For the study, Wanhe Li first compared how flies fare under various lockdown conditions. After seven days, flies housed together in groups of varying sizes produced no anomalous behaviors. Even two flies cut off from the crowd were content with one another. But when a single fly was entirely isolated, the lonely insect began eating more and sleeping less.

Further investigation revealed that a group of genes linked to starvation were expressed differently in the brains of lonely flies -- a tempting genetic basis for the observed connection between isolation and overeating.

Li then found that a small group of brain cells known as P2 neurons were involved in the observed changes to sleep and feeding behavior. Shutting down the P2 neurons of chronically-isolated flies suppressed overeating and restored sleep; boosting P2 in flies isolated from the group for only one day caused them to eat and sleep as if they had been alone for a full week.

"We managed to trick the fly into thinking that it had been chronically isolated," says Wanhe Li. "The P2 neurons seem to be linked to the perception of the duration of social isolation, or the intensiveness of loneliness, like a timer counting down how long the fly has been alone."

The Young lab painstakingly confirmed these observations. They engineered insomniac flies, to make sure that lack of sleep alone did not cause overeating (it didn't). They tested group-reared flies to find out whether manipulating P2 neurons would cause overeating and sleep loss in socialized flies (it doesn't). Ultimately, they concluded that only a perfect storm of both P2 neuron activity and social isolation will cause flies to begin to losing sleep and overeating.

Explaining the "Quarantine 15"

Scientists have observed that many social animals -- from fruit flies to humans -- eat more and sleep less when isolated. The reason for this is unclear. One possibility, Young says, is that social isolation signals a degree of uncertainty about the future. Preparation for tough times may include being alert and awake as often as possible and eating whenever food is available.

This study can hardly confirm that humans in COVID-19 lockdowns ate more and slept less due to the same biological mechanisms that keep lonely flies hungry and sleep deprived. But now that Li and Young have identified the neurons and genes responding to chronic isolation in fruit flies, future researchers can search for corresponding connections between loneliness, overeating, and insomnia in laboratory animals and, eventually, humans.

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Scientists show what loneliness looks like in the brain

 

Person sitting alone on bench.

This holiday season will be a lonely one for many people as social distancing due to COVID-19 continues, and it is important to understand how isolation affects our health. A new study shows a sort of signature in the brains of lonely people that make them distinct in fundamental ways, based on variations in the volume of different brain regions as well as based on how those regions communicate with one another across brain networks.

A team of researchers examined the magnetic resonance imaging (MRI) data, genetics and psychological self-assessments of approximately 40,000 middle-aged and older adults who volunteered to have their information included in the UK Biobank: an open-access database available to health scientists around the world. They then compared the MRI data of participants who reported often feeling lonely with those who did not.

The researchers found several differences in the brains of lonely people. These brain manifestations were centred on what is called the default network: a set of brain regions involved in inner thoughts such as reminiscing, future planning, imagining and thinking about others. Researchers found the default networks of lonely people were more strongly wired together and surprisingly, their grey matter volume in regions of the default network was greater. Loneliness also correlated with differences in the fornix: a bundle of nerve fibres that carries signals from the hippocampus to the default network. In lonely people, the structure of this fibre tract was better preserved.

We use the default network when remembering the past, envisioning the future or thinking about a hypothetical present. The fact the structure and function of this network is positively associated with loneliness may be because lonely people are more likely to use imagination, memories of the past or hopes for the future to overcome their social isolation.

"In the absence of desired social experiences, lonely individuals may be biased towards internally-directed thoughts such as reminiscing or imagining social experiences. We know these cognitive abilities are mediated by the default network brain regions," says Nathan Spreng from The Neuro (Montreal Neurological Institute-Hospital) of McGill University, and the study's lead author. "So this heightened focus on self-reflection, and possibly imagined social experiences, would naturally engage the memory-based functions of the default network."

Loneliness is increasingly being recognized as a major health problem, and previous studies have shown older people who experience loneliness have a higher risk of cognitive decline and dementia. Understanding how loneliness manifests itself in the brain could be key to preventing neurological disease and developing better treatments.

"We are just beginning to understand the impact of loneliness on the brain. Expanding our knowledge in this area will help us to better appreciate the urgency of reducing loneliness in today's society," says Danilo Bzdok, a researcher at The Neuro and the Quebec Artificial Intelligence Institute, and the study's senior author.

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