In the last decade or so, Merikangas tells WebMD, ''it seems to me there has not been much research attention" on the topic.
With her colleagues, she examined data from a national representative sample of U.S. adolescents, known as the National Comorbidity Survey Replication Adolescent Supplement. The sample included face-to-face interviews with more than 10,000 teens ages 13 to 18.
The study is published online in the Archives of General Psychiatry.
Prevalence of Eating Disorders in Teens
Anorexia nervosa is marked by self-starvation and excessive weight loss. Bulimia involves a cycle of bingeing and then compensating for overeating by self-inducted vomiting or other behaviors. Binge eating disorder is marked by recurrent binge eating without compensating behaviors.
For lifetime prevalence, the researchers found:
- For anorexia, about 0.3% of the teens were affected (55,000). For bulimia, about 0.9% (170,000).
- For binge eating, about 1.6% (300,000).
When the researchers looked at 12-month prevalence, they found lower rates, with 0.2% of teens affected with anorexia, 0.6% for bulimia and 0.9% for binge eating.
The sample was cross-sectional, a kind of snapshot in time, says Merikangas. But in her own review of the medical literature, comparing those findings with the new data, she says that anorexia has remained fairly stable since 1990, while bulimia and binge eating have both increased about twofold.
The researchers also looked at what is known as ''subthreshold'' eating disorders. "We also discovered a wide range of people who have some of these behaviors but didn't reach the threshold of either severity, duration, or frequency that we have somewhat arbitrarily applied [to the definition of each]."
They had enough information to identify ''subthreshold'' anorexia and binge eating, finding about 3.3% of the teens had one of these.
Eating Disorders: Boys vs. Girls
Among the surprises of the study, Merikangas tells WebMD, is ''we didn't have a big sex difference for anorexia." About 0.3% of both boys and girls were affected for lifetime prevalence.
For bulimia and binge eating, many more girls than boys were affected, they found.
The most surprising, to Merikangas, was that ''one-third of those with bulimia had actually attempted suicide." About 15% of those with binge eating had and about 8% of those with anorexia had attempted suicide.
She found most of the teens sought treatment, but only a minority got treatment specifically for the eating disorder. It speaks to the stigma that still exists, she says.
"People still have a lot of shame about these conditions," she says.
Her advice for parents? Seek professional help sooner rather than later if they suspect eating disorders.
Eating Disorders: Seek Expert Help
The study results had some surprises for James Lock, MD, PhD, a professor of child psychiatry and pediatrics at the Stanford University School of Medicine, who recently published a study about self-injurious behavior in teens with eating disorders.
"To me the lack of a sex difference in anorexia is really surprising," he says.
The research, he tells WebMD, ''points out how common, how severe these disorders are, not only in the area of the eating disorders but also the coexisting psychiatric illnesses, the higher amount of suicidal behavior and thought, and associated medical problems."
If parents suspect an eating disorder in their child, Lock tells them to seek an evaluation by their medical doctor, ''and if the symptoms persist by an expert in eating disorders."
"Don’t forget," he adds, ''that boys can have these problems.''