Sticks and stones may break your bones, but names can hurt just as much. Indeed, according to converging evidence reported in a new review in Current Directions in Psychological Science, physical and social pain are processed in some of the same regions of the brain.
Naomi Eisenberger, co-director of the Social Cognitive Neuroscience Lab at UCLA, published the first brain-imaging paper revealing the overlap in 2003. She had been studying participants’ reactions to being rejected by other players (actually just a computer opponent) in a video game. “The first time we noticed the similarity, I was analyzing data next to a colleague of mine who was analyzing data on physical pain in irritable bowel syndrome,” she says. “We noticed similarities in the way that the neural data looked.”
Physical pain has two components, Eisenberger explains: sensory and emotional. The sensory part of physical pain is mapped in the brain depending on which part of the body is hurt, but the emotional component — how distressing your brain determines the pain to be — is registered in the dorsal anterior cingulate cortex (dACC). That’s also where the sting of social pain is processed.
“The affective component, which tells you more how much the pain is bothering [you], how much suffering it is causing — that experience seems to be more localized to the dACC and the anterior insula,” Eisenberger says.
The dACC, which is rich in receptors for endorphins, the brain’s natural opioids, is also directly affected by opioid drugs including heroin and Oxycontin. That may help explain why one of the most common reports from patients who take such painkillers is not that their pain has disappeared entirely, but rather than it doesn’t torment them anymore. A similar experience is reported by chronic pain patients whose suffering is so intractable that they resort to brain surgery to remove parts of the dACC. “The patients will say, ‘Well, I can still feel [the pain], but it doesn’t bother me,’” Eisenberger notes.
Eisenberger has found that even non-opioid pain-relievers like acetaminophen (Tylenol) can ease social pain. In a study published in 2010, her group showed that people taking Tylenol for three weeks not only reported less hurt feelings than those taking placebo, but also showed reduced brain activation in the dACC in response to rejection.
“By nine days you see differences between the two groups emerge and they stay that way for the rest of the study,” Eisenberger says.
That time lag may explain in part why Tylenol hasn’t become a popular street drug like opioids. Although drug users are always seeking new substances to dull their emotional pain, they tend to favor instant results — addicted people use their drugs of choice to escape feelings of social rejection and emotional angst now, not nine days from now. The same phenomenon may also help explain why slow-acting antidepressants, despite their ability to reduce people’s sensitivity to social slights, are also not misused.
“It would be interesting to do more studies” on Tylenol, Eisenberger says, especially since rejection sensitivity is a key symptom of depression. Perhaps acetaminophen and even other drugs like aspirin may have hitherto unsuspected antidepressant properties. Though all drugs have side effects, she suggests that those safe enough to be sold over the counter might have some advantages, particularly for mild to moderate depression.
Of course, no one is proposing that people start taking Tylenol to prevent social pain. The fact that social pain exists — and that it relies on the same regions of the brain as physical pain — suggests that it is a necessary experience. It is likely key in helping to keep animals in social species connected to one other, by making rejection feel distressing and social nurture feel soothing.
Although the connection between physical and emotional pain is now widely accepted, the first suggestions that painkilling drugs might have an emotional effect were warily viewed. In the 1970s, Jaak Panksepp found that in experiments with rats, baby animals’ distress over separation from their mothers was soothed by morphine; it was conversely increased by naloxone, a drug that prevents opioids from acting.
But Panksepp had difficulty publishing his findings because of the association between morphine and addiction. He once told me that editors of Science rejected his first paper on the subject as “too hot to handle,” telling him essentially that if his research later proved incorrect, comparing a mother’s love to a shot of heroin would have been offensive.
Since then, research has repeatedly shown that the effect of opioids mimic the rewarding warmth of relationships and that the feelings of social rejection are aligned with the anxiety of withdrawal.
Eisenberger also found that people with a gene that makes them more sensitive to physical pain are also more sensitive to social rejection. Unsurprisingly, this common gene codes for an opioid receptor.
The relationship between emotional and physical pain goes both ways: just as physical pain-relieving drugs can kill emotional pain, so too can emotional support — for example, holding a loved one’s hand — reduce physical pain.
Research even shows that emotional pain can sometimes activate brain regions that normally process only physical hurt. One recent study of people who had just been dumped by a romantic partner found that intense rejection activated somatosensory brain regions once thought to be involved only with physical sensation.
Although the researchers didn’t ask, I suspect that the subjects would have said they felt the pain in their hearts.