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If your mother has diabetes, you probably watch your children pretty carefully to make sure they maintain a healthful diet. The results of a recent study show that you should do the same if your family has a history of anorexia nervosa.
Cynthia Bulik, a professor of eating disorders, and Carolina scientists Patrick Sullivan, Federica Tozzi, and Helena Furberg, collaborated with researchers at the Karolinska Institute in Sweden and found that about 56 percent of the liability for developing anorexia rests in the genes.
The team used data stored in the Swedish Twin Registry, the largest twin registry in the world. “It’s an amazing world resource,” Bulik said, and one that is maintained in a country that’s dedicated to using national health information for the public good. The researchers were able to access data from a huge sample of twins — 31,406 individuals born between 1935 and 1958. Roughly half of the twins in the representative sample were genetically identical, or monozygotic; the other half were fraternal, or dizygotic, and genetically distinct.
The researchers wanted to know how often both twins in a pair suffered from anorexia. By linking data from the registry to death and hospital discharge records, they were confident that they identified all cases of anorexia nervosa. The team found that both members of the identical twin pairs had the disorder more frequently than did both members of the fraternal twin pairs.
“That suggests there’s a genetic component to the disorder,” said Bulik.
They also found that childhood neuroticism was the strongest predictor of the development of anorexia nervosa. These tend to be anxious and depressed kids, Bulik said, who may be highly functional and get straight As, “but inside, they’re just wired very tight.” They’re like emotional Velcro, she said. They have high emotional reactivity to things that usually just roll off other kids’ backs.
Take a classroom full of your average sixth graders. The media, their peers, and other environmental factors will persuade about 60 percent of those kids to go on a diet in the near future.
Most of them will give it up after a few days, and some will stick to it for a little longer, and then possibly overcompensate by binge eating. For a few of those kids who are genetically predisposed to anorexia nervosa, Bulik said, “that diet might lead to a paradoxical decrease in their anxiety and their dysphoria.”
It might be, she said, that food deprivation is calming for them.
But those kids will have a higher chance of developing anorexia later — or sometimes sooner — in life.
“We suggest that there are some basic biological differences between people who are prone to anorexia nervosa and everybody else,” Bulik said. “When most of us get hungry, or starved, we get more anxious. But these people’s bodies respond differently. They say that food deprivation makes them feel more calm and more in control, which is one reason they keep doing it.”
For decades, doctors have blamed bad parenting for the development of anorexia nervosa in young people, and believed it to be a sickness of choice.
“This research needs to help remove the whole detrimental theory that parents cause this disorder,” Bulik said. “And that somehow these girls and boys and women and children simply choose to starve themselves.
“Biology takes on a life of its own,” she said. “The train just starts running.”
Provided by Research and Economic Development.
Editor: Neil Caudle
Writer: Margarite Nathe