Anorexia a Family Affair

Study shows genetic link also holds true for men

TUESDAY, March 27 -- Women whose sons or brothers have anorexia show a much greater risk of developing the eating disorder themselves, new research says.

Scientists already knew that female siblings of women with anorexia have a heightened risk of the condition. The latest study, which appears in the April issue of the International Journal of Eating Disorders is the first to show it also holds true for males.

Anorexia occurs in between 0.1 percent and 0.6 percent of females. The percentage is lower for males, although the exact number isn't known.

Michael Strober, of the University of California at Los Angeles, and his colleagues studied 29 male anorexics and 747 of their relatives, along with 181 women without eating problems.

While the boy's male relatives weren't at higher risk for the condition, the women in their family were 20 times more likely than normal to have the eating problem, and about three times more likely to have a mild version of the disease. Other eating disorders, such as bulimia, weren't more common in either male or female relations. In all, there was nine-fold increased risk of some form of anorexia among close female relatives of men with the disease.

The results point to a genetic cause.

"The familial pattern would suggest either significant stressful factors that run in families, or heritability of risk," Strober says. "The weight of evidence from other studies of other [psychological] diseases would suggest that genetic factors account for a significant aspect" of risk.

One explanation that seems less likely, says Strober, is that dangerously abnormal eating habits are learned. And while dieting undoubtedly has cultural roots, anorexia doesn't appear to be the result of societal pressures to be thin. These messages, in the form of ads, movies, television and other media, are omnipresent, Strober says. "But only a very small minority [of people] develop anorexia."

Dr. Barton Blinder, an eating disorders expert, says he's "not surprised" by the UCLA findings.

"There's no reason why that shouldn't exist," Blinder says, unless the anorexia gene or genes are located on the X, or uniquely female, chromosome.

Blinder adds he has seen male patients with anorexia whose parents -- both mother and father -- and female siblings also have the disease.