Loneliness hurts!
Did you know that loneliness is so psychologically distressing and physically unhealthy that it increases the likelihood of an earlier death by 26 percent?
The flip side of that is that this feeling may serve a purpose. Psychologists theorise it hurts so much because, like hunger and thirst, loneliness acts as a biological alarm bell. The ache of it drives us to seek out social connection just as hunger pangs urge us to eat. The idea is intuitively satisfying…yet it has long proved difficult to test in humans.
On 26th March, however, just as the COVID-19 pandemic gripped the world, researchers from the Massachusetts Institute of Technology posted a preliminary report on the bioRxiv website (see reference below). It is the first study in humans to show that both loneliness and hunger share signals deep in a part of the brain that governs very basic impulses for reward and motivation. The findings point to one telling conclusion: our need to connect is apparently as fundamental as our need to eat.
The extraordinary scientific timing of the paper’s release just as tens of millions of people were suddenly starved for contact was far from intentional. When they began the work three years ago, neuroscientists Livia Tomova and Rebecca Saxe and their colleagues wanted to demonstrate how loneliness operates in the brain. They were inspired by similar research in animals and the pioneering loneliness studies of the late University of Chicago psychologist John Cacioppo.
But enforced social isolation is so rare in healthy, nonincarcerated humans that it gave the team pause for thought. They wondered what it would be like in the real world if that ever were to happen…and then why would this ever happen. By the time the researchers came to write their study this year, the unimaginable had become real.
This is a tour de force paper. It suggests that chronic social isolation might be something like long-term undernourishment, producing steady, aversive need that wears away at our well-being. These findings give a name to what countless people are experiencing right now: social craving while staying at home to protect the greater public health.
The paper, which has not yet been peer-reviewed, describes a carefully designed experiment using functional magnetic resonance imaging (fMRI) to compare brain responses to loneliness and hunger. After a baseline brain scan, 40 adult participants underwent a 10-hour session depriving them of food and another 10-hour session denying them social contact. Both session served as a control condition for each other.
The social-isolation condition was challenging to arrange. Some people are lonely in a crowd, while others enjoy solitude. To induce not just objective isolation but subjective feelings of loneliness, the researchers had the participants spend their time from 9 A.M. to 7 P.M. in a sparsely furnished room at the laboratory without phones, laptops or even novels in case fictional characters provided some social sustenance. Puzzles were allowed, as was preapproved nonfiction reading or writing. During the food-deprivation day, the subjects could not to eat or drink anything but water over the same time frame.
Brain scanning immediately followed each deprivation session, yet measuring the relevant brain signals was also challenging. Tomova and Saxe focused on a midbrain region called the substantia nigra, a center of dopamine release involved with motivation and craving. Because an fMRI signal from the substantia nigra is indirect, the researchers designed a cue-induced craving task similar to what is used in addiction research. When drug addicts are shown cues associated with their substance of choice, they show a strong desire response. It’s long been established that this triggers this dopamine response.
In the scanner, the participants saw images of their preferred forms of social interaction and of their favorite foods, as well as a control image of flowers. The researchers found that this brain area specifically responded to the cues after deprivation but only to cues of what they had been deprived of. The magnitude of the response correlated with the subjects’ self-reports of how hungry or lonely they were, though the feelings of hunger were consistently stronger.
Finally, the researchers used machine learning to confirm their findings. A software classifier trained to recognise neural patterns during fasting proved able to recognise similar neural patterns from the social-isolation condition even though it had never “seen” them. This suggests that there seems to be an underlying shared neural signature between the two states. Social contact is a very basic need.
Even before the COVID-19 pandemic, an obvious next question for the work was whether different forms of social media could satisfy the need for social connection. Saxe and Tomova were never able to get funding for such a study. But it seems likely they will now! Tomova is already working with researchers at the University of Cambridge, where she will move later this year, to see if social media use during the pandemic might be remediating feelings of loneliness.
So if you’re feeling lonely and frustrated, take heart. You’re not alone.
Let’s take this opportunity to recognise the importance of relationships for our health and to practice leveraging technology for social well-being.
And we will get through this – together!
References
Tomova et al. The need to connect: Acute social isolation causes neural craving responses similar to hunger. https://www.biorxiv.org/content/10.1101/2020.03.25.006643v2