social craving: desire for connection is like hunger
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new research looked closely at our brains when we don't have much human interaction.
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absence may make the heart grow fonder but isolation just makes the brain hungry, according to a team of neuroscientists that say the human desire for social interaction rivals the cravings a starving person feels for food.
the study, conducted at the massachusetts institute of technology, found that segregation from family and friends leads to increased neural activity in the same part of the brain that goes haywire when you park a pizza in front of someone who hasn’t eaten all day. the finding has taken on added importance in the age of isolation brought to us courtesy of covid-19.
“our finding fits the intuitive idea that positive social interactions are a basic human need, and acute loneliness is an aversive state that motivates people to repair what is lacking, similar to hunger,” said rebecca saxe, the study’s senior author and a professor of brain and cognitive sciences at mit, according to science daily.
the team’s research was based on data from 2018 to 2019 — before the pandemic — and part of larger research into the effects of social stress on human behaviour. while previous studies have connected isolation to emotional distress, the underlying mechanisms are not fully understood.
“we wanted to see if we could experimentally induce a certain kind of social stress, where we would have control over what the social stress was,” saxe said. “it’s a stronger intervention of social isolation than anyone had tried before.”
to achieve the necessary level of stress, researchers recruited 40 healthy college students and confined them to windowless rooms on mit’s campus for 10 hours at a time. they were not allowed to use their phones and could only use a computer in the room to contact the team if they needed assistance. “there were a whole bunch of interventions we used to make sure that it would really feel strange and different and isolated,” saxe said.
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“they had to let us know when they were going to the bathroom so we could make sure it was empty. we delivered food to the door and then texted them when it was there so they could go get it. they really were not allowed to see people.”
after the 10 hours expired, the subjects were required to enter an mri machine, which researchers had previously taught them how to use in an attempt to minimize social contact. “normally, getting somebody into an mri machine is actually a really social process,” saxe said. “we engage in all kinds of social interactions to make sure people understand what we’re asking them, that they feel safe, that they know we’re there.
“in this case, the subjects had to do it all by themselves, while the researcher, who was gowned and masked, just stood silently by and watched.”
during the mri, subjects had their brains scanned while looking at three types of images: pictures of food, pictures of people interacting, or neutral images, such as flowers. the participants were also given another mri on a different day after fasting, but not isolating, for 10 hours. researchers focused their attention on the substantia nigra, a structure located in the midbrain long linked to food and drug cravings.
true to their hypothesis, the “craving signal” in this small area of the brain was the same for participants regardless of whether they had been deprived of food or social contact. the amount of brain activity correlated to how strongly participants later rated these cravings.
interestingly, the team found that baseline levels of subject loneliness factored into how strong their cravings were. “for people who reported that their lives were really full of satisfying social interactions, this intervention had a bigger effect on their brains and on their self-reports,” saxe said.
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the scans also revealed that other parts of the brain — such as the striatum and the cortex — were activated differently depending on the craving, which suggests these areas deal with more specific longings versus the general cravings registered in the substantia nigra.
armed with their findings, researchers now hope to explore how isolation specifically impacts human behaviour, how different age groups are affected and if virtual contacts, such as zoom meetings, can alleviate their longings. they also intend to follow up with their subjects to see if they can predict how specific individuals handled covid-19 lockdowns based on their mris.
“previous research has shown that when chosen intentionally, solitude can have positive effects on wellbeing,” said livia tomova, one of the study’s authors and a post-doctoral fellow at mit. “however, currently people have little choice about whether to isolate or not and while some people might not mind as much, others might suffer from feeling disconnected with others.”
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