Adolescent girls with eating disorders are at risk of also developing anxiety disorders, and vice versa, according to a new study.

Dr. Pamela K. Keel, of the University of Iowa, Iowa City, and colleagues examined the simultaneous occurrence of eating disorders and mood disorders among 672 female twins (ages 16 to 18 years) from the Minnesota Twin Family Study.

The subjects completed structured interviews that determined the presence of anorexia or bulimia, and assessed mood, anxiety, and substance use.

Eating disorders were highly likely to co-exist with major depression, anxiety disorders, and nicotine dependence, the investigators report in the International Journal of Eating Disorders.

Within a group of 14 identical twin pairs who did not both have an eating disorder, the risk for anxiety disorders was nonetheless increased among the non-eating-disordered co-twins.

Conversely, among 52 identical twin pairs of whom only one had anxiety disorder, those without anxiety disorders had an increased risk for eating disorders

“These results suggest that eating disorders and anxiety disorders share familial risk factors,” Keel said in an interview with Reuters Health. “The next step would be to examine whether the shared transmission is explained by genetic or environmental factors or a combination of both.”

Keel added that “the participants in the study were young (and) it is likely that some of the participants who did not have mood disorders or substance use disorders may develop these problems in the future.”

She concluded, “As participants move through the period of risk for developing different kinds of mental disorders, we might find evidence of shared transmission between eating disorders and other types of mental disorders.”

SOURCE: International Journal of Eating Disorders, September 2005.