Genetics Found to Play Role in Eating Disorders

Two new studies show that genetics may outweigh environmental factors in causing the eating disorders involved in anorexia and bingeing.

“This is good news for patients and their families,” said Cynthia Bulik of the University of North Carolina School of Medicine. In a recent issue of the Archives of General Psychiatry, Bulik and colleagues studied records from 30,000 Swedish twins, some with anorexia, and found that identical twins, who have identical genes, were more likely to share an eating problem than were fraternal twins, who, like non-twin siblings, share only half their genes.

In this large sample, scientists determined that genes were responsible for 56% of the cases of the potentially life-threatening condition. Anorexics have symptoms that include self-starving and an obsessional belief that they are fat.

Bulik and others are trying to identify genetic risk factors so they can better solve this puzzling eating behavior.

“We have gone through far too much time blaming parents,” Bulik said. “People need to understand that they are fighting their biology” and not just a psychological need to be thin.

Once genes are identified, scientists hope to develop drugs that work directly on them.

In another study published in the same journal, a team of investigators at McLean Hospital, a Harvard affiliate, found a strong genetic contribution to binge eating. Binge eating is far more common than other eating disorders, involving 2% to 5% of the population. Binges are characterized by compulsive, episodic eating of large amounts of food in a short period.

Dr. James Hudson, director of the biological psychiatry laboratory at McLean and an associate professor of psychiatry at Harvard Medical School, recruited 300 people, half with a history of binge eating, then set out to interview their parents, children and siblings. They found that family members of binge eaters were twice as likely to have a similar eating disorder than those without a such a history. And the relatives of binge eaters were more than twice as likely to be obese than people who didn’t share that eating behavior.

In another study, Bulik found that people with anorexia said that starving themselves made them calmer. Normally, hunger triggers anxiety.