Why A Broken Heart Really Hurts

Researchers have found a genetic link between physical pain and social rejection, which means that breaking up with a partner really can be painful!

Psychologists at the University of California, Los Angeles say the human body has a gene which connects physical pain sensitivity with social pain sensitivity. The findings back the common theory that rejection 'hurts' by showing that a gene regulating the body's most potent painkillers - mu-opioids - is involved in socially painful experiences too.

Their study indicates that a variation in the mu-opioid receptor gene (OPRM1), often associated with physical pain, is related to how much social pain a person feels in response to social rejection. People with a rare form of the gene are more sensitive to rejection and experience more brain evidence of distress in response to rejection than those with the more common form.

Researchers collected saliva samples from 122 participants to assess which form of the OPRM1 pain gene they had and then measured sensitivity to rejection in two ways. First, participants completed a survey that measured their own sensitivity to rejection. They were asked, for example, how much they agreed or disagreed with statements like "I am very sensitive to any signs that a person might not want to talk to me." Then the emotions of 31 people among the group were tested when they were excluded during a virtual ball-tossing computer game.

Study co-author Prof Naomi Eisenberger said: "Individuals with the rare form of the pain gene, who were shown in previous work to be more sensitive to physical pain, also reported higher levels of rejection sensitivity and showed greater activity in social pain-related regions of the brain when they were excluded."

This is the first time that it has been proved that genes involved in physical pain are linked to mentally painful times like social rejection and breaking up with a lover. Co-author Baldwin Way said: "These findings suggest that the feeling of being given the cold shoulder by a romantic interest or not being picked for a schoolyard game of basketball may arise from the same circuits."

Prof Eisenberger said this overlap in the neurobiology of physical and social pain makes perfect sense. She said: "Because social connection is so important, feeling literally hurt by not having social connections may be an adaptive way to make sure we keep them. "Over the course of evolution, the social attachment system, which ensures social connection, may have actually borrowed some of the mechanisms of the pain system to maintain social connections."

The research is published by the Proceedings of the National Academy of Sciences.