A wealth of science over the last few years has drawn clear lines between loneliness and poorer health, both physical and psychological. Feeling lonely leads to stronger feelings of social isolation, and those feelings are extremely damaging, particularly over time as the effects compound.
Now a new study asks whether loneliness also leads to shorter-term health effects, like worse symptoms for the common cold. Specifically, it looked for a link between perceived social isolation—the main dynamic of loneliness—and how hard people were hit by their colds.
"This paper is about the quality of your relationships, not the quantity," said study co-lead Angie LeRoy. "You can be in a crowded room and feel lonely. That perception is what seems to be important when it comes to these cold symptoms."
The study included about 160 people ages 18-55. All were first psychologically and physically assessed to rate their overall health, and were also scored on the Short Loneliness Scale and the Social Network Index, tools used to gauge loneliness. Then all of the participants were given cold-inducing nasal drops and quarantined in hotel rooms for five days.
The results showed that those who reported greater loneliness on the scales were no more likely to catch a cold than anyone else. But those with the highest loneliness scores who developed colds experienced the most severe symptoms.
Importantly, the correlation did not exist with the sizes of the peoples’ social networks (how many people they said they actually interact with), but correlated strongly with their perceived social isolation—their feelings of loneliness despite how many people are orbiting their lives.
"Previous research has shown that different psycho-social factors like feeling rejected or feeling left out or not having strong social bonds with other people do make people feel worse physically, mentally and emotionally," LeRoy said. "So we had that general framework to work with."
This was an unusually well-structured study in that it actually caused and then observed the connection it was studying (giving people colds and keeping them in a hotel room for days ranks as rigorous in my book), but on the downside the study didn’t include a healthy control group to compare against. That would have made it even stronger.
Nevertheless, the results do point to a connection that’s turned up in a lot of past research and this study adds to the chorus: Loneliness is dangerous. Perceived social isolation is a negative health factor, and it appears to be becoming more so even as our digitally bloated social networks continue inflating.
The study was published in the journal Health Psychology.