It's no secret that rejection hurts. So it's a good thing our brains have a system in place that acts as a social "painkiller," according to a new study.
Researchers from the University of Michigan Medical School found that the brain's mu-opioid receptor system -- which is already known to release opioid chemicals in response to physical pain -- also releases opioids in response to social rejection.
"This is the first study to peer into the human brain to show that the opioid system is activated during social rejection," study researcher David T. Hsu, Ph.D., a research assistant professor of psychiatry at the university, said in a statement. "In general, opioids have been known to be released during social distress and isolation in animals, but where this occurs in the human brain has not been shown until now."
The findings, which are published in the journal Molecular Psychiatry, are based on brain imaging conducted on 18 adult study participants. The participants were set up in a faux online-dating scenario, where they looked at pictures and read fictitious profiles of other adults, and then selected who they found most romantically desirable. The participants were all aware that the profiles and photos were fake.
Then, researchers put the study participants in a PET scanner to conduct brain imaging. While the participants were lying in the scanner, they were told that the person they thought was attractive didn't like them back. Researchers found a release of opioid chemicals in the brain, particularly in the brain regions linked with physical pain (the amygdala, midline thalamus, periaqueductal gray and ventral striatum).
There also seemed to be a link between the resiliency of the participant and the response by the opioid systems. People who scored higher on a resiliency trait test seemed to "be capable of more opioid release during social rejection, especially in the amygdala," Hsu noted. "This suggests that opioid release in this structure during social rejection may be protective or adaptive."
Interestingly, opioids were also released in the brain when participants were told that a person they liked liked them back, highlighting opioids' dual role in both decreasing pain and increasing pleasure.
Social rejection has been shown in past research to actually be bad for health. A study in the journal Clinical Psychological Science, published last year, showed that social stressors could negatively affect the immune system.
And a 2011 study also from University of Michigan researchers showed that pain from social rejection and physical pain "hurt" similarly in the brain.