We’ve all felt isolated at times, but the so-called “invisible epidemic” that is loneliness is about much more than ephemeral feelings of sadness.
For decades, researchers have been seeing signs that the immune systems of lonely people are working differently.
Loneliness is now linked to everything from heart disease, depression, to Alzheimer’s disease and cancer.
A study suggests that’s because the pain of loneliness activates the immune pattern of a primordial response commonly known as fight or flight.
Lonely people’s white blood cells seem to be more active in a way that increases inflammation, a natural immune response to wounding and bacterial infection. On top of that, they seem to have lower levels of antiviral compounds known as interferons.
That seemed to provide a link to a lot of the poor health outcomes associated with loneliness, since chronic inflammation has been linked to everything from cancer to depression.
The human body isn’t built to hold a high level of inflammation for years, and therefore this is making you ill.
Steve Cole, a genomics researcher at the University of California, Los Angeles, and lead author on the study published in the Proceedings of the National Academy of Sciences said,
That explains very clearly why lonely people fall at increased risk for cancer, neurodegenerative disease and viral infections as well.”
Not only this, but they have discovered that prolonged loneliness can change how your body works.
To find that out, Cole and his collaborators tracked 141 people over five years.
Every year, the researchers measured how lonely the participants felt and took blood samples to track the activity of genes involved with immunity and inflammation.
They also tracked concentrations of the hormone norepinephrine, one of the two main signals during the flight-or-fight response.
Cole noticed that when people felt lonesome, they had significantly higher levels of norepinephrine coursing through their blood.
That could explain all the other immune changes that happen when people suffer from social isolation.
In a life-threatening situation, norepinephrine cascades through the body and starts shutting down immune functions like viral defence, while ramping up the production of white blood cells called monocytes.
It’s this surge in these pro-inflammatory white blood cells that are highly adapted to defend against wounds, but at the expense of our defenses against viral diseases that come from close social contact with other people,”
At the same time, lonely people seem to be shutting down genes that would make their bodies sensitive to cortisol, which lowers inflammation. That ramps up the defensive inflammation response.
Loneliness would hit the switch on a defence plan our bodies initiate in the face of mortal danger, Cole thinks, if isolation is somehow truly lethal.
At this point, my best guess was that loneliness really is one of the most threatening experiences we can have. Though I didn’t think of loneliness as being that awful. It’s not pleasant, but not something my body should be getting all up in arms about.”
In the world of cubicles and studio apartments, loneliness is everywhere. We find it in both crowds and empty rooms. We change cities and lose friends. Even in relationships, people can be strangers to one another. But things were very different for our ancestors. When humans were evolving in a prehistoric environment, they banded together for food and for protection.
To be ostracised from your tribe was a death sentence, says Charles Raison, a psychiatrist at the University of Wisconsin-Madison who did not work on the study.
Literally they would die. There was no human way to live in isolation.”
Being alone in the wild meant you could be mauled by angry animals or angry human beings. Then your body would need extra defences against wounds and infection, but less protection against viruses you get from other people, like the flu. In that case, the stressful response to loneliness would simply be the body’s way of trying to survive exile.
The findings of this study have been published in Proceedings of the National Academy of Sciences.