Does Dieting, Stress and Genetic Risk Factors Influence Anorexia?
In a new mouse study performed by researchers from Columbia University Medical Center (CUMC), it appears certain genetic and environmental risk factors can trigger compulsive food restriction, much like what’s seen in individuals with anorexia.
The findings of this new study could help to identify new prevention and treatment strategies for eating disorders in humans. For a long time, researchers have suspected a combination of genetics, biological, sociocultural and psychological variables increased a person’s risk of anorexia. However, none were ever able to capture the elements of social stress and genetic predisposition to anorexia that appears to contribute to the onset of the disorder in humans, particularly in youngsters.
Dr. Lori Zeltser, associate professor of pathology & cell biology and a researcher at the Naomi Berrie Diabetes Center said, “We think that for the first time, we have a mouse model of anorexia that closely resembles the conditions leading up to the disease in humans. And this model not only shows us the most important factors that contribute to the onset of anorexia, it’s also helping us to identify signaling pathways in the brain that ultimately drive this potentially fatal eating disorder.”
Anorexia is the third most common chronic illness in adolescent aged males and females in the United States. It has a lifetime prevalence ranging from 0.3 to 0.9 percent in females and 0.1 to 0.3 in males. This eating disorder has a mortality rate of 8 to 15 percent, the highest of any psychiatric disease. There is currently no cure for the disease.
For the new mouse study, the research team exposed adolescent mice with at least one copy of the variant BDNF gene, which has been linked to anorexia and anxiety in mice and humans. The mice were also exposed to social stress and caloric restriction.
Dr. Zeltser stated, “One driver of anorexia in humans is peer pressure, specifically, the desire to be thin. People assumed that you couldn’t replicate that in a mouse. We decided to take peer pressure out of the equation and focus on social stress, which can be accompanied by housing mice alone, instead of in groups.”
The mice were put on a calorie-restrictive diet, which precedes the development of anorexia in adolescents and it can act as a trigger for an eating disorder. In the study, the impact of the diet was simulated by reducing the mice’s calorie intake by 20-30 percent, roughly the equivalent to the calorie reduction in humans.
The Results of the Study
Dr. Zeltser said, “Our findings show that having the at-risk genotype alone is not sufficient to cause anorexia-like behavior, but it confers susceptibility to social stress and dieting, especially during adolescence. You need a lot of variables in place to see this robust effect on eating behavior.”
The CUMC research team is currently using the new mouse model to study signaling pathways in the brain which may drive anorexic behavior, with the ultimate goal identifying new treatment options to help those suffering with an eating disorder.