For the last decade researchers have found
that emotional pain experienced from social rejection activates the same region
of the brain that physical pain activates – the pain center. (see previous post "The Science of Pain, Empathy and Emotion)
Scientists believe that
since mammals live in social groups that are crucial to survival, social
rejection is akin to a physical threat to our brain. A recent paper by Hsu et
al. from the University of Michigan, has now shown that the same opioid
receptors located in the brain’s pain center activated in response to physical
pain are also activated by emotional pain and that the more opioid response an
individual releases, the more that person scores high on the trait
“resiliency”. The study also found that the brain rewards social
acceptance with activation of opioid receptors located elsewhere in the brain.
The brain protects itself
from feeling too much physical pain by dosing itself with endogenous opioids.
It lets you feel pain so you know that whatever it is you are doing should
stop, but then alleviates its own pain by activating opioid receptors located
in the pain center of the brain. Presumably, this neat self-soothing mechanism
exists so when we get hurt we don’t just lie down and cry. (My personal experience points to the failure of this quenching or dampening of pain; the result is panic and anxiety that will escalate to unbearable levels.)
Given the
similarities in the experience of physical and emotional pain, scientists have
hypothesized that emotional pain also results in opioid receptor activation. In
this study, Hsu and Zubieta used a radiotracer specific for opioid receptors to
visualize the release of endogenous opioids with PET imaging in response to
stimuli.
Expectedly, rejected
subjects felt more “sad and rejected” and less “happy and accepted,” while
accepted subjects felt the opposite. Interestingly, subjects with high opioid
activity rated themselves as lower in the “sad and rejected” scale. These
findings suggest that individuals with a robust opioid response bounce back
more quickly in the face social rejection. This data corroborates a study by
Way et al. from 2009 which examined the differences in activation of the
brain’s pain center in response to social rejection between people who have a
normal opioid receptor gene and those who have a mutation in the receptor. The
mutated receptor is thought to have greatly reduced function and carriers of
this mutation have been shown to need greater amounts of opioids to treat
physical pain (ex: post-surgical pain). Way and Eisenberg saw that carriers of
the mutation had greater activation of the pain center than non-carriers.
These findings will
hopefully lead to new therapies and interventions with individuals suffering
from depression, social anxiety, and other psychological disorders.
Hsu, D. et al. Response of the μ-opioid system to social rejection and acceptance. Molecular psychiatry 18, 1211–7 (2013).
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