Can Loneliness Kill You? – Member Feature Stories – Medium
Back in the late 1980's, psychologist Steve Cole was trying to find what makes some gay men more likely to die from AIDS than others. "He looked at the obvious—age, socioeconomic status, overall health, sleep quality, exercise habits, sex life, anxiety levels, depression history—but none of these predicted who would get AIDS or how soon they’d die."
But he found one odd risk factor: gay men who hid their identities were more likely to die of AIDS than gay men who didn't, and those who hid their identities were more sensitive to social rejection than those who didn't. "For a long time, researchers had observed a curious link between social isolation and a number of diseases, from heart disease to cancer to some neurodegenerative disorders." Could that be due to more socially connected people being prodded into being healthier by social pressure?
But Cole’s research showed that bad habits weren’t actually wrecking his subjects’ health. The gay men who contracted AIDS were just as physically fit and mentally well as those who resisted the disease. There seemed to be something else, something more direct, that was stripping some participants’ immune defenses and leaving them fatally exposed to the virus.
Then a study of old people.
The results were remarkable: The immune systems of the lonely subjects behaved differently from those of the non-lonely—and dramatically so. For instance, the lonely subjects’ antiviral defenses were partially shut down, which suggested a possible reason for why socially sensitive gay men were so vulnerable to HIV. But that wasn’t where the damage ended. In addition to suppressing the body’s innate defenses against viruses, loneliness also seemed to crank up inflammation to dangerous levels, raising the risk of myriad diseases.
Inflammation is part of the immune system's response toward wayward bacteria: "It’s the redness, swelling, and heat you experience when you injure yourself, and it’s what keeps infection from spreading throughout your body." However,
Prolonged inflammation has long been known as a risk factor for infectious diseases, but around the time that Cole and Cacioppo began their collaboration, other researchers started to link inflammation to a host of non-infectious illnesses, from asthma to arthritis, diabetes, cancer, Alzheimer’s, and depression. A 2012 review of the clinical literature suggested that chronic inflammation may, in fact, lie at the root of many more diseases than initially thought. “Perhaps,” the researchers concluded, “even all of them.”
... The lonely subjects’ immune systems had switched from their default antiviral mode to a chronic injury-fighting mode, leaving them exposed to both viral infections and inflammation-related diseases.
Expanding this research reveals
So far, research suggests that the situations that most reliably predict a dangerous surge of inflammation involve social rejection and loss. The health impact of divorce, for example, depends largely on who initiates it: If it’s your spouse, you not only lose an important relationship but feel rejected, which will derail your immune system more than if the decision to end the marriage came from you.
A 2010 meta-analysis of 148 studies concluded that being lonely is not only bad for your health, it’s in fact significantly worse than drinking or not exercising. Loneliness emerged as a risk factor for early death with an impact as significant as smoking and three times more significant than obesity.
Then some speculations on why loneliness might have evolved. Contrary to the rugged-individualist pretensions of some of us, we are a highly social species. So loneliness would be like hunger, a warning that we lack something vital. Loneliness would also provoke readiness to deal with injuries -- inflammation.
Still, as far as loneliness goes, the research suggests that the factual reality of it impacts our immune system in a different way—and to a smaller extent—than our subjective experience.
Indeed when he speaks of loneliness, Cacioppo defines it as perceived, rather than objective, social isolation. The distinction makes sense.
...
Despite the fact that technology has connected us to a degree never before seen in history, we’re still as lonely as ever. Most researchers estimate that between 20 and 30 percent of people are chronically lonely. One study finds that, among Londoners, that number is closer to 50 percent. Loneliness is also universal. It can equally affect both introverts and extroverts, says Cacioppo, and the only difference between them is the number of close relationships required to feel connected (one for introverts versus three for extroverts).
But other people may not be good to be around -- they can be troublesome.
Sensitivity to social threats may, in fact, be even more deeply etched into biology than a desire for connection. Consider the evolution of our sense of taste. We are far more sensitive to bitter than we are to sweet, says Cacioppo, because throughout history bitter tastes often meant poison. A strong visceral reaction against bitter ensured that we stay away from foods that could kill us.
Similarly, a built-in negative bias against other humans would have protected us from miscalculated friendship.
Not surprisingly, we have a lot of variation.
People low in social motivation, for example, tend to feel quite happy on their own or with just a few close friends. We call them introverts, and their experience is not so much loneliness as solitude.
For people high on social motivation, the reverse is true: They need a larger number of social ties in order to feel connected, and the absence of these ties can plunge them into deep loneliness.
Then about how negative social bias can become a self-fulfilling prophecy -- being suspicious of others may provoke what one is suspicious of. This can lead to an inflammation response that eventually needs no triggers -- and causes lots of trouble.
