Oxytocin Receptor Gene, Socioeconomic Status and Childhood Obesity
Recent work by UCSF researchers in the Division of Developmental Medicine suggests that children raised in low socioeconomic status environments who have a genetic variant for the oxcytocin receptor may be at increased risk for childhood obesity.
In a paper published in JAMA Pediatrics, the researchers described how body weight was more likely to be affected either positively or negatively by socioeconomic status (SES) in children with the A form (allele) of the oxytocin receptor gene. Compared to children with the G allele, who had moderate rates of obesity irrespective of SES, children with the A form were much more likely to be obese if they were of low SES but much less likely to be obese if their SES was high.
“As a field, we have thought of children as either “vulnerable” or “resilient” to socioeconomic conditions,” said Division Chief Tom Boyce, MD. “But this work indicates that it may be more helpful and informative to consider the relative sensitivity of kids to their socioeconomic environment.”
The findings fit into an increasingly popular theory of differential neurobiological susceptibility, which holds that some individuals are more sensitive than others to both positive and negative environmental factors.
Childhood obesity currently affects almost 1 in 5 children in the United States, putting them at risk for physical, social, and psychological problems as they age. Low socioeconomic status has a longstanding and strong association with obesity risk across the lifetime, one that may occur through its relation to factors such as lower birth weight, lack of access to health care, limited availability of healthy foods and places to exercise, and increased exposure to environmental stresses such as noise, crowding, toxins and violence.
The paper’s lead author, Nicole Bush, PhD, who is associate director for research for the division, became interested in how genetics might confer individual differences in responses to socioeconomic adversity during her postdoctoral studies at UCSF and UC Berkeley. Oxytocin has been shown to promote antistress physiological responses and is also associated with appetite and weight in both animal models and studies with human adults. This study, funded through Bush’s participation in the Robert Wood Johnson Foundation Health & Society Scholars Program, is among the first to look at the role of the oxytocin receptor gene in child obesity, said Bush.
Participants were drawn from the Peers and Wellness Study (PAWS) led by Dr. Boyce, a larger, ongoing project that enlisted families from San Francisco Bay Area public school classrooms to examine the effects of social status on health. Families were assessed during the children’s kindergarten year (2003-2005) and again during middle school (2009-11). Children’s physical data was collected through anthropometric measures (body mass index and triceps skin fold), DNA was collected via saliva samples, and family socioeconomic status was measured with questionnaires. A total of 186 socioeconomically and racially/ethnically diverse children, approximately equally divided between males and females, were included in the study.
“Socioeconomic status is powerfully linked to so many risk factors for poor health. Studies like this can help us understand who is more at risk for the association between low socioeconomic status and obesity and point to opportunities for intervention,” said Bush.