UCLA psychologists have determined that a gene linked with physical pain sensitivity is also associated with social pain sensitivity. Their study indicates that variation in the opioid receptor gene (OPRM1), often associated with physical pain, is also related to how much pain a person feels in response to social rejection. Published in the Proceedings of the National Academy of Sciences, the new finding could explain why some of us are acutely sensitive to rejection as those with a rare form of the gene are much more sensitive to rejection than others with the more common form.
In the study, the researchers collected saliva samples from the participants to assess which form of the OPRM1 gene they had and then measured their sensitivity to rejection in two ways. First, participants completed a survey that measured their self-reported sensitivity to rejection.
Next, a subset of this group was studied using functional magnetic resonance imaging (fMRI) during a virtual ball-tossing game in which participants were ultimately socially excluded. Subjects were told that they would be connected over the Internet with two other players who were also in fMRI scanners and that they would all be playing the interactive ball-tossing game. In reality, however, participants were playing with a preset computer program, not other people. Initially, participants were included in the activity but were then excluded when the two other "players" stopped throwing the ball to them.
"What we found is that individuals with the rare form of the OPRM1 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 - the dorsal anterior cingulate cortex and anterior insula - in response to being excluded," UCLA's Naomi Eisenberger said.
The researchers say that the biological overlap of physical and social pain makes good sense, evolutionary speaking. "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," explained Eisenberger. "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."
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Source: University of California - Los Angeles
