Oxytocin's role in binge eating

Oxytocin is an evolutionarily ancient molecule produced in the brain that acts at sites throughout the body by triggering the OXTR. It influences many survival behaviors including those used to manage stress, according to Dr. Caroline Davis, the lead researcher on the study. "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."

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 group had a broad range of body weights and included a substantial number with binge-eating habits. Among other measures, a blood sample was collected from each participant in order to analyze their DNA, the molecules that carry each individual's unique genetic information.

The DNA analysis uncovered a new link 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 correlated with the OXTR genetic information.

The researchers tested the prediction 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% of the variance in overeating," says 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."