In different people, the gene for the oxytocin receptor (OXTR) may carry a smaller or larger number of epigenetic modifications known as DNA methylation tags. People who are low in DNA methylation may be better able to utilize oxytocin, the so-called love hormone. People who are high in DNA methylation may have an exaggerated fear response.
This finding, which emerged from a study conducted by scientists at the University of Virginia, suggests that epigenetic markers may be used more generally to predict social behaviors. Perhaps multiple types of markers could even result in a kind of emotion-predisposition dashboard, predicting problems and prompting interventions.
The study appeared February 9 in the Proceedings of the National Academy of Sciences, in an article entitled, “Epigenetic modification of the oxytocin receptor gene influences the perception of anger and fear in the human brain.”
“High levels of OXTR methylation were associated with greater amounts of activity in regions associated with face and emotion processing including amygdala, fusiform, and insula,” wrote the article’s authors. “Importantly, we found that these higher levels of OXTR methylation were also associated with decreased functional coupling of amygdala with regions involved in affect appraisal and emotion regulation.”
Essentially, the study indicated that individuals with lower DNA methylation show diminished brain response to angry and fearful faces and greater communication between brain regions important for regulating emotion. To arrive at this result, the study evaluated sample of 98 healthy Caucasians aged 18 to 30 who provided blood samples and underwent functional MRI brain scans while looking at pictures of angry and fearful faces.
The researchers identified a relationship between the level of DNA methylation in an individual and activity in the amygdala and other parts of the brain responsible for emotion processing.
“Our findings highlight the importance of including epigenetic mechanisms in the description of the endogenous oxytocin system and further support a central role for oxytocin in social cognition,” the authors concluded. “This approach linking epigenetic variability with neural endophenotypes may broadly explain individual differences in phenotype including susceptibility or resilience to disease.”
The research team hypothesizes that this may be important for understanding the state of the disrupted or diseased brain as individuals with autism spectrum disorder, psychopathy, depression, and anorexia nervosa all display high degrees of DNA methylation at the oxytocin receptor.
“Defining biomarkers like this epigenetic tag associated with the oxytocin receptor may help us to predict future social developmental problems and inform interventions for those with social deficits,” said co-author Jessica J. Connelly, Ph.D., a University of Virginia assistant professor of psychology.
The investigators believe it is possible that eventually a blood test could be developed that would, in effect, predict how a person would behave in various social situations. Dr. Connelly and her colleagues are sorting through the complexities of epigenetics—the nature-and-nurture question of how both genetics and environment affect psychological development.