Chronic Social Isolation Reshapes Brain Chemistry, Loneliness Study Shows

Being lonely sucks. Sure, we all need our alone time now and then, but scientists have repeatedly found that, as social animals, prolonged loneliness is bad for us. In 2016, scientists found the physical locus of loneliness in the brain, and now, as research on this eternal human affliction continues, scientists have discovered that the stress of chronic social isolation can actually reshape the brain.

Whereas much of the research on isolation and stress involves behaviors, the Cell paper, published Thursday, looks at a lesser-studied factor: the brain chemicals involved in loneliness. It showed that mice experiencing the stress of spending two weeks in social isolation had elevated levels of a brain-signaling molecule called Tac2, which in turn increases levels of a neuropeptide called NkB. The abundance of this molecule, the researchers write, might be responsible for all of the stressed-out behaviors they noticed in the mice. “It’s a neuropeptide that’s conserved across a number of species, and at least in mice and fruit flies, it seems to be involved in some aspects of social isolation,” Moriel Zelikowsky, Ph.D., a neuroscience postdoc at Caltech and the first author on the new study, tells Inverse. Human brains have very similar pathways to those of mice, which suggests that the findings will hold true for us, too.

The signs of stress the isolated mice exhibited included higher levels of anxiety and exaggerated responses to potential threats. Further supporting the hypothesis that Tac2 and NkB are to blame, the study’s authors showed that mice who were given a drug that inhibits the action of those molecules did not show signs of isolation stress under the same circumstances. To put it simply, this study shows evidence that there are chemical changes in the brains of mice that experienced long-term social isolation — and, importantly, that these changes can be blocked.

“It’s definitely in a position to be readily translatable to humans for targeted therapies,” Zelikowsky says, explaining that the antagonist drug the team gave the mice during their periods of isolation effectively lessened the negative effects of the isolation. This suggests that, while the effects of loneliness show up as psychological stress, they can be managed with neuroscience and pharmacology.

Zelikowsky says that a therapy like this one, which targets only a single type of brain receptor, could eventually be much more effective and cause fewer side effects than drugs like the currently available antidepressants, which act on huge systems in the brain. She sees this research as particularly relevant now, with increasing levels of social isolation among young people and old people alike.

“Much like they’re trying to target cancer drugs to just cancerous cells,” she says, “this could target a specific subset of cells producing abnormal behaviors, some of which are detrimental to the quality of life we’d all like to have.”