UCLA scientists have conducted a study that for the first time gives weight to the popular argument that rejection really does “hurt”. They have determined that a gene that was previously linked to physical pain is associated with “social pain’ sensitivity as well.

The gene is question is the mu-opioid receptor gene, or OPRM1, The study was able to show that a variation in this gene is related to the amount of social pain an individual experiences. Patients with a rare form of the gene were found to be more emotionally sensitive to rejection and exhibit more brain evidence of distress than those with the more typical form.

During the course of the study the researchers collected saliva sample from the voluntary participants in order to determine which variation of OPRM1 they personally possessed. After this was determined the participants had their sensitivity to rejection measured in two different ways.

First they were asked to complete a survey designed to measure their self assessed sensitivity to rejection. They were asked how much they agreed or disagree with certain set statements such as “I am very sensitive to any signs that a person might not want to talk to me.”

Next, a subset of the overall group, 31 people, was studied using functional magnetic resonance imaging at UCLA’s Ahmanson–Lovelace Brain Mapping Center. The participants were studied while participating in a virtual ball tossing game, from which they were ultimately excluded. They were all told that they were “playing” with two other human participants hooked to scanners in other rooms, although the reality was that they were playing with a preset computer program alone.

The game began with the subject being included in the game, but they were then excluded when the two other “players: stopped throwing the ball to them and tossed it only amongst “themselves”.

“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,” said Naomi Eisenberger, who is UCLA assistant professor of psychology and director of UCLA’s Social and Affective Neuroscience Laboratory and a co author on the study.

The dorsal anterior cingulate cortex and anterior insula are both regions of the brain that have been previously associated with the distress caused by physical pain.

“Although it has long been suggested that mu-opioids play a role in social pain — and there are convincing animal models that show this — this is the first human study to link this mu-opioid receptor gene with social sensitivity in response to rejection,” Eisenberger said.