TUESDAY, March 7, 2006 (HealthDay News) -- Anorexia nervosa, one of the most common problems facing young women, seems to have a strong genetic component.
New research, involving 31,406 Swedish twins who were born between Jan. 1, 1935, and Dec. 31, 1958, suggests that 56 percent of the risk for developing the eating disorder is inherited, and the condition is linked with neurotic symptoms -- such as anxiety or depression -- early in life.
"For centuries, we have been under very false stereotypes and misconceptions about what causes anorexia nervosa," said study author Cynthia M. Bulik, the William and Jeanne Jordan Distinguished Professor of Eating Disorders and director of the Eating Disorders Program at the University of North Carolina.
Her report appears in the March issue of the Archives of General Psychiatry.
Anorexia nervosa features a fear of becoming obese, an aversion to food, and the highest death rate of any mental illness, the study noted.
It was believed that young women and men chose anorexia nervosa so they could look like models or achieve some societal goal, Bulik said. "But there is something deeper and more biological that's driving this behavior. There is a substantial genetic component to liability for anorexia nervosa."
Many more women than men suffer from anorexia, Bulik noted. About 1.2 percent of women have the condition, compared with 0.29 percent of men.
Bulik's team also found that one of the factors that predicted anorexia nervosa was neurotic behavior. "We are talking about people who are prone to anxiety and depression, and people who are emotionally reactive," she said.
Using data from questionnaires given in the early 1970s, the researchers examined seven potential predictors of anorexia among women -- body mass index, stomach problems, excessive exercise, perceived stress, an extroverted personality and neuroticism, emotional instability, and feelings of depression, anxiety and guilt. Only neuroticism was found to be a risk factor for anorexia.
Bulik said that genetics lay the groundwork for the condition, but something in the environment triggers it. "Genes load the gun, and environment pulls the trigger," she said. "These people who are genetically disposed to anorexia nervosa may be more sensitive to those environmental triggers, like dieting after seeing a fashion magazine."
The researchers also found there were more cases of anorexia among those born after 1945.
If the genes that lead to anorexia nervosa can be identified, then there might be treatment implications, such as medications, Bulik said.
"Anorexia nervosa is not simply a disorder of choice," Bulik said. "There is a clear genetic [cause] for this disorder that we need to incorporate into our understanding of what anorexia nervosa is."
"We also need to look out for those young children who are anxious and depressed," she advised. "They may be on the path to developing an eating disorder later in life."
One expert thinks there may be more environmental triggers now, which has led to increased cases of anorexia.
"Bulik and colleagues make a meaningful contribution to the field in a large study of twins that reveals both genetic and environmental contributions to the development of anorexia," said David L. Katz, an associate professor of public health and director of the Prevention Research Center at Yale University School of Medicine.
In addition, the association between neuroticism and the disorder might help identify people at risk for anorexia, Katz said.
The most noteworthy finding is that anorexia is more frequent now than it was in past decades, Katz said.
"While some of this association may relate to better detection, the study methods suggest that it is a real trend," Katz said. "We thus have yet another indication that the combination of unrealistic standards of beauty propagated in the media in conjunction with powerfully obesigenic forces conspires against both physical and mental health."
More information
The National Eating Disorders Association can tell you more about anorexia nervosa.
