Variants of the oxytocin receptor (OXTR) gene may be linked to certain personality traits at high risk for overeating and binge eating, according to a new study by researchers at York University and the Centre for Addiction and Mental Health (CAMH) in Canada.
OXTR is triggered by the powerful hormone and neurostransmitter oxytocin at various sites throughout the body. Oxytocin plays an important role in bonding and childbirth and influences many survival behaviors including those used to manage stress.
“For example, oxytocin enhances prosocial and related behaviors. On the other hand, increases in oxytocin tend to decrease appetite — especially the consumption of sweet carbohydrates,” said lead researcher Dr. Caroline Davis at York University.
For the study, the researchers investigated how the OXTR gene influences appetite, food preferences, food intake, and personality risk traits associated with brain-reward mechanisms.
Over the past decade, Davis and her co-investigator Dr. James Kennedy, director of the Department of Neurogenetics at CAMH, assessed a large group of participants ranging in age from 27-50 years.
The participants, who had a broad range of body weights, included a substantial number of people with binge-eating habits. Among other measures, the researchers collected a blood sample from each participant in order to analyze their DNA, the molecules that carry each individual’s unique genetic information.
The DNA analysis revealed a new association between oxytocin and behaviors associated with binge eating. The researchers focused on seven sites in the DNA where chemical instructions for making OXTR could vary between individuals.
These “single nucleotide polymorphisms” (SNPs) were already suspected to be associated with psychological traits. The researchers collected questionnaires about their participants’ differences in reward sensitivity, punishment sensitivity, sugar/fat food preferences, and overeating habits, to be compared to the OXTR genetic information.
The researchers tested the hypothesis that these SNPs relate to psychological risk factors, which in turn are associated with overeating behaviors.
“Three SNPs were significantly related to the psychological traits, which collectively accounted for 37 percent of the variance in overeating,” said Davis. “Another SNP was directly related to overeating. These results support the role of genes in giving rise to traits that regulate behavior, and highlight the importance of oxytocin in overeating.”
The new findings were presented at the Annual Meeting of the Society for the Study of Ingestive Behavior (SSIB), the group for research into all aspects of eating and drinking behavior.