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(Ivanhoe Newswire) A genetic variation may contribute to how empathetic a person is and how that person reacts to stress.
A variation in the receptor of the hormone/neurotransmitter oxytocin was linked to a person's ability to infer the mental state of others. This same genetic variation also related to stress reactivity. These findings could significantly add to knowledge about oxytocin and its link to conditions such as autism and unhealthy levels of stress.
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Oxytocin is a peptide secreted by the pituitary gland and regulated by the hypothalamus of the brain. It is best known for its role in female reproduction -- it is important for labor and breastfeeding, for instance. It is also associated with social recognition, pair bonding, dampening negative emotional responses, trust and love.
There are three possible combinations of this genetic variation of the oxytocin receptor. All humans get one copy of the gene from each parent, thus the three possible combinations, labeled as AA, AG or GG allele. The AA and AG gene group were not statistically different, so they were grouped together and compared in all tests with the GG group.
Sarina Rodrigues, co-author and assistant professor of psychology at Oregon State University, was quoted as saying that oxytocin has already been linked with social affiliation and reduction in stress. Rodrigues and colleagues studied 200 college students of diverse ethnicity and balanced gender. The students filled out questionnaires and participated in laboratory-based sessions.
The tests included a standard stress reactivity test involving white noise blasts directed in headphones after countdowns presented on a screen. Heart rate was monitored throughout the laboratory session. In general, researchers found that women were more sensitive to the stress tests, but that both men and women in the GG allele group displayed a lower increase in heart rate compared to baseline heart rate measured at the beginning of the laboratory session.
One of the tests used to measure empathy included the "Reading the Mind in Eyes" test, created by Simon Baron-Cohen, cousin of actor/comedian Sacha Baron Cohen. Rodrigues said this tests how well the participant can infer someone's emotional state by looking at their eyes.
"In general, women do better on this test than men," Rodrigues was quoted as saying. "But we found a stark difference in both sexes based on the genetic variation." Those with the GG genetic variation were 22.7 percent less likely to make a mistake on the "Reading the Mind in the Eyes" test than the other individuals.
Rodrigues said previous research has shown that people with autism display lower scores on behavioral and dispositional empathy measures, and that a nasal spray with oxytocin increases scores in these areas.
"Our data lends credence to the claim that this genetic variation of oxytocin influences emotional processing and other-oriented behavior," she said.
However, Rodrigues cautioned against drawing too many conclusions just yet, that there are plenty of people in the AA or AG gene pool who are empathetic, caring individuals.
"I tested myself, and while I am not in the GG group, I'd like to think that I am a very caring person with empathy for others," said Rodrigues. "These findings can help us understand that some of us are born with a tendency to be more empathic and stress reactive than others, and that we should reach out to those who may be naturally closed-off from people because social connectivity and belongingness benefits everyone."
SOURCE: Proceedings of the National Academy of Sciences (PNAS), November 16, 2009
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