Rejection and heartbreak can have effects every bit as physical as cuts and bruises, and understanding why could change your life.
It is only in the past 10 years that we have begun to unravel the basis of these hurt feelings in the brain. Scientists have found that the sting of rejection fires up the same neural pathways as the pain from a burn or bruise. Besides explaining why some people have thicker skins than others, this fact reveals an intimate link between your social life and your health - you really can die of loneliness.
Our language has long borrowed physical terms to describe our darkest emotions, with phrases such as “she broke my heart”, “he burned me”, and “he stabbed me in the back”. Such comparisons occur around the world: Germans talk about being emotionally “wounded”, while Tibetans describe rejection as a “hit in the heart”.
Although these expressions were always taken to be metaphorical, there had been some early hints that more was afoot. Animal studies in the 1990s, for instance, showed that morphine not only relieves pain after injury, but can also reduce the grief of rat pups separated from their mother.
The dorsal anterior cingulate cortex (dACC) region is known to be an important part of the brain’s “pain network”, determining how upsetting we find an injury. The response can vary depending on the situation; bumping your head might seem like a big deal in the office, but during a football game you might barely notice the blow.
Crucially, the more distressing you find an injury, the more the dACC lights up, those who reported feeling worst after the rejection showed the greatest activity in this region.
Other studies confirmed the link, finding that social rejection provokes not just the dACC but also the anterior insula, another part of the pain network that responds to our distress at a cut finger or broken bone. But although these results all suggest that our anguish after an insult is the same as our emotional response to an injury, it took until last year to show how those feelings might spill over into tangible bodily sensations.
Ethan Kross at the University of Michigan recruited 40 people who had been through a break-up within the past six months and asked them to view a photo of their ex while reclining in an fMRI scanner. He also instructed them to think in detail about the break-up. After a brief intermission, the volunteers’ forearms were given a painful jolt of heat, allowing Kross to compare brain activity associated with the two situations.
As expected, the dACC and the anterior insula lit up in both cases. But surprisingly, the brain’s sensory centres, which reflect the physical discomfort that accompanies a wound, also showed pronounced activity - the first evidence that the feeling of heartbreak can literally hurt (PNAS, vol 108, p 6270).
Cementing the connection between physical pain and emotional anguish, further studies have found that the two experiences sometimes feed off one another. When people feel excluded, they are more sensitive to the burn of a hot probe, and submerging a hand in ice water for 1 minute leads people to report feeling ignored and isolated.
Numbing the hurt
The converse is also true: soothing the body’s response to pain can alleviate the sting of an insult. Nathan DeWall of the University of Kentucky, Lexington, recruited 62 students who either dosed themselves up on two paracetamol (acetaminophen) pills every day for three weeks, or took a placebo. Each evening, the students completed a questionnaire measuring their feelings of rejection during the day. By the end of the three weeks, the group on paracetamol had developed significantly thicker skins, reporting fewer hurt feelings during their day-to-day encounters.
"The idea that you can actually affect people’s experience socially with what is seen as such a mild, common drug [as paracetamol], that was a rather important validation," says Geoff MacDonald at the University of Toronto, Canada, one of the authors of the study. "This is exactly the kind of thing you would expect if this social pain thing is really true." Needless to say, due to the harmful side-effects of pain-killing drugs, you should not try this for yourself.
The work might explain why certain people find it harder to withstand the rough and tumble of their social lives than others. Extroverts have been shown to have a higher pain tolerance than introverts, and this is mirrored by their greater tolerance for social rejection.
These diverse reactions may be partly genetic. Eisenberger’s team has shown that people with a small mutation to the gene OPRM1, which codes for one of the body’s opioid receptors, are more likely to slip into depressed feelings after rejection than are those without the mutation. This same mutation also makes people more sensitive to physical pain, and they typically need more morphine following surgery.
Importantly, these receptors are particularly dense in the dACC. As you might expect, in people with the mutation, the dACC tends to react more strongly to perceived insults (PNAS, vol 106, p 15079).
When you consider our ancestors’ dependence on their social connections for survival, it makes sense for us to have evolved to feel rejection so keenly. Being kicked out of a tribe would have been akin to a death sentence, exposing our predecessors to starvation and predation. As a result, we needed a warning system that alerts us to a potential spat, preventing us from causing
further offence and teaching us to toe the line in the future. The pain network, able to give us a jolt when we face physical injury from a fire or knife edge, would have been ideally equipped to curb our social behaviour.
Some have taken this line of thinking further, suggesting it might hold the secret to some of the more mysterious symptoms of loneliness. People who are lonely tend to have an increase in the expression of genes for inflammation, particularly in immune cells, and a decrease in the expression of antiviral genes.
Why would the body deal with isolation in this way? “That was kind of a puzzle to us for the last five or 10 years,” says Steve Cole, a behavioural geneticist at the University of California, Los Angeles. An answer began to emerge when he looked at the way different conditions affect people with different social lives. Viruses spread quickly among large groups of people, whereas life-threatening bacterial infections generally come from wounds which our ancestors may have been more likely to receive when alone, without the protection of their peers. As a result, Cole suggests, our immune system may be “listening in” on our brain’s signals of social status. If it looks as if we are enjoying a lively social life in a big group, we are geared up to deal with viruses; if we feel alone, the dACC and other regions tune up inflammation, which helps us battle bacterial infection.
(via New Scientist)