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Eating Disorders Can Be a Family Trait

March 3, 2000 (Boston) -- Nature appears to have the edge over nurture when it comes to the eating disorders anorexia nervosa and bulimia nervosa, say authors of two studies published in the March issue of The American Journal of Psychiatry.

Anorexia, which usually occurs in young women and teen-agers, is an extreme, abnormal fear of weight gain that leads people who suffer from it to starve themselves. They have a distorted body image in which they see themselves as being obese even when they are dangerously thin and malnourished. Bulimia nervosa is characterized by binge eating that is often followed by self-induced vomiting and feelings of guilt and shame; it, too, occurs most frequently in young women.

The first study found that anorexia nervosa and bulimia nervosa both occur more frequently in close family members of women with the disorders than in the relatives of women who have never had the eating disorders. The second study, conducted in young adult women who were either fraternal or identical twins, also suggests that there are sets of genes that may predispose people who inherit them to develop anorexia, major depression, or both.

In the first study, Michael Strober, PhD, and colleagues from the University of California, Los Angeles, and Western Psychiatric Institute in Pittsburgh studied nearly 2,000 first-degree relatives (sisters or mothers) of 504 young adult women with either anorexia or bulimia and a control group with no history of eating disorders.

The researchers found that relatives of women with anorexia were 11.4 times more likely to have anorexia than were relatives of women in the control group. Similarly, relatives of women with bulimia had a 3.7 times greater risk for bulimia than the family members of controls. Women with less severe forms of the eating disorders were also more likely to have relatives with the conditions.

The evidence also suggests that the disorders have at least some features in common, says Strober, professor of psychiatry and director of the eating disorders program at the Neuropsychiatric Institute and Hospital at the UCLA School of Medicine. "What was significant, I think, was the relationship between the two disorders -- that comes out very strongly in our data, as did the likelihood of [less severe forms of the disorder] being transmitted as well," he tells WebMD.

The authors also found that relatives of bulimic women had a 12.1 times higher risk for anorexia than others, and family members of anorexic women were 3.5 times more likely to have bulimia than the relatives of people without an eating disorder. This shows how strongly the two disorders are linked.

Anorexia also appears to share a family history with depression, suggest researchers from Virginia Commonwealth University (VCU) in Richmond, who looked at family ties and concurrent incidence of anorexia and major depression among female identical and fraternal twins.