Eating Disorders May Run in Families
Pattern Seen in Studies of Anorexia, Binge Eating
March 6, 2006 -- The eating disorders anorexia and binge eating may run in families, according to two new studies.
Both studies appear in the Archives of General Psychiatry. The first study showed that genetic factors accounted for more than half of anorexia cases among more than 31,000 twins in Sweden.
"We were able to show for the first time that there is a substantial genetic component to anorexia nervosa," researcher Cynthia Bulik, PhD, tells WebMD.
The second study showed that binge eating tends to run in families. Genes might be at work, but the study doesn't prove that.
"Basically, what we're finding out is that eating disorders are familial disorders," says Bulik, who worked on both studies and is an eating disorders expert at the University of North Carolina (UNC).
Bulik, who led the anorexia study, directs the UNC Eating Disorders Program. She is also the William and Jeanne Jordan Distinguished Professor of Eating Disorders at UNC's psychiatry department and a professor of nutrition at UNC's School of Public Health.
"For a long time, people have viewed anorexia nervosa as a disorder of choice," Bulik says. "People thought that these were people choosing to lose a lot of weight and diet down to some thin ideal."
She adds that people have also blamed parents and parenting styles "for far too long" for causing anorexia.
Her study included 31,406 twins in Sweden who were screened in 2002 for anorexia and other problems. A total of 1.2% of the women and 0.29% of the men had anorexia.
Anorexia and Genes
Genes appeared to be a big influence on the odds of developing anorexia.
"The way I say it is that 56% liability for developing anorexia nervosa is due to genetic factors and the remaining is due to the environment," Bulik says. "Environment" means factors besides genes.
However, "this is not a one-gene disorder," Bulik says. "We will never find one gene that causes anorexia nervosa. It's a complex trait, and that's a real scientific term which means it's influenced by multiple genes and multiple environmental factors."
Environmental influences -- like cultural emphasis on thinness -- still counts. "I think what this genetic research will lead us to is a better understanding of who is more sensitive to the environmental triggers," Bulik says.