For some diseases, taking a census is easy. Most people who have cancer are diagnosed with the disease before they die and seek treatment, allowing for the collection of detailed national cancer statistics. But other diseases tend to hide in the shadows, undetected and under-counted due to infrequent diagnosis or an unwillingness of patients to seek treatment. Into this latter group falls the eating disorders: anorexia nervosa, bulimia nervosa, and other conditions. Because many of these patients try to avoid treatment, psychiatrists have long suspected the numbers are skewed because only a subset of people suffering from eating disorders find their way to their clinical practice.
“We only see the tip of the iceberg,” said Daniel Le Grange, professor of psychiatry and director of the University of Chicago Eating Disorders Program. “As clinicians and researchers, we’ve known that in the community there are thousands of people out there with eating disorder behaviors that we never see in our clinics.”
Hard data on the frequency of eating disorders in the broader community has been hard to come by. But a new survey study of over 10,000 adolescents, released last week in the Archives of General Psychiatry, confirmed that the iceberg of eating disorder prevalence among American teens is as broad below the surface as psychiatrists suspected. Almost 6 percent of those surveyed in the study met the criteria for one of the five eating disorders tested at some point in their lifetime, a number extrapolated by some media outlets to 500,000 teens in the United States.
But the total numbers were just one of the eyebrow-raising results of the research. Le Grange, a co-author on the study, sat down with ScienceLife and detailed the most significant findings of this long-awaited census, and discussed its implications for the nature of these diseases and the patients who are slipping through the field’s fingers.
1. The Myth of Rarity
Health care dollars are not infinite, and cynical as it may sound, diseases must compete for research funding and insurance reimbursements. So when conditions such as eating disorders are perceived as rare occurrences, the people who treat and study those conditions face an uphill struggle for attention and support. Thus, the under-reporting of eating disorder prevalence has held the field back from being considered as a priority concern in adolescents. The new numbers – lifetime prevalences of 0.3% for anorexia nervosa, 0.9% for bulimia nervosa, 1.6% for binge-eating disorder, and 3.3% for sub-threshold disorders – lift eating disorders into a higher tier of concern for teenage and adult health.
“The myth has been that eating disorders and especially anorexia nervosa are relatively rare disorders, and we constantly have to argue that they’re not, because that’s what it feels like when we sit in clinical practice and we are inundated by patients,” Le Grange said. “This is robust data to demonstrate that eating disorders are not rare.”
2. A Gender-Blind Illness
In the clinic, psychiatrists see far more girls with eating disorders than boys – a ratio of 9-to-1. But surprisingly, the community survey revealed roughly equal prevalence for anorexia nervosa in males and females, suggesting that boys are not less likely to suffer from the condition, but are much less likely to be diagnosed and treated. Le Grange said he suspects that physician bias may lead them to more quickly consider an eating disorder when the patient is a she rather than a he.
“We are so convinced that anorexia nervosa is predominantly a female disorder that pediatricians and mental health professionals, when presented with a boy who’s lost weight, do not consider anorexia to be a legitimate diagnosis,” he said. “When we do see boys in our clinic, they usually have had an extensive preliminary workup, as the clinicians don’t consider an eating disorder…until everything comes back negative.”
3. Effects Beyond Mealtime
Psychiatrists observe that eating disorders don’t typically occur in isolation, as patients often carry “co-morbid” psychiatric issues such as depression or anxiety. The community survey puts a number on this observation, finding that the majority of those that met the criteria of an eating disorder also met the criteria of at least one other psychiatric disorder. Perhaps most alarming was the very high occurrence of suicidal thoughts and attempts in adolescents with eating disorders – more than half of those with bulimia nervosa reported thinking about suicide, and more than a third reported attempts.
Also striking was that these associations were just as common for kids who exhibited “sub-threshold” eating disorders, those did not meet the full criteria for anorexia nervosa or bulimia nervosa. In the DSM-IV, the diagnostic bible of psychiatry, such patients would be lumped into the category of Eating Disorders Not Otherwise Specified (EDNOS). The health risks associated with these patients suggest that EDNOS should not be seen as any less severe an illness, Le Grange said.
“The EDNOS kids presented with as many co-morbid disorders and suicidality as AN and BN kids,” he said. “So they might not meet full criteria for number of binges or amount of weight loss, but in every other regard they are as seriously unwell.”
4. Slipping Through the Cracks
The good news: most adolescents with eating disorders reported receiving at least some treatment for emotional or behavioral issues. The bad news: only about a quarter of them, at best, received treatment specific for eating disorders. That strange juxtaposition suggests widespread missed opportunities for clinical intervention, Le Grange said, as teenagers are treated for depression or behavioral problems but not the underlying or associated eating problems.
Some of the patients who got away may have been boys, for the reasons stated above. But another group slipping through the clinical net may be minority patients, who are typically under-represented in American psychiatric clinics. Whether due to socioeconomic factors or different cultural perspectives on psychiatric illness, African-American and Hispanic patients are less likely to be referred for eating disorder treatment, Le Grange said. But the survey found no significant differences between races on qualifying for eating disorders, and even found a higher prevalence for bulimia nervosa among Hispanic adolescents.
5. A Pre-Teen Concern
Much of the research into the epidemiology of eating disorders is conducted in adults. So when researchers want to determine when the disorder began, they must rely upon the subjective memory of their patients, who estimate when they first began to struggle with food. The new study, by surveying teens instead of adults, offered an opportunity to get a more accurate estimate for the ages of onset in different eating disorders. The results pushed those ages even younger than before, with the medians for four of the five disorders falling into age 12. While anorexia nervosa was already thought to arise in early adolescence, the finding that bulimia also often begins before a patient’s teens was a surprise to some in the field, Le Grange said.
“It’s a striking finding that suggests one shouldn’t wait until the early twenties to identify bulimia nervosa, but to start looking for it in early teens instead,” he said.
All in all, Le Grange expected the study to significantly affect perceptions of eating disorders both within the field of psychiatry and without, in the greater population at large. The research certainly hit a nerve, as hundreds of articles had already been written about the paper in the week following its publication. The majority of these articles accurately conveyed the most important implications for eating disorders, Le Grange said.
“The main story is these disorders are prevalent, far more than we thought previously, and these kids are unwell in several domains, far more than we perhaps previously thought,” Le Grange said. “We were correct to think that who we see in our clinics are the tip of the iceberg, and that in the population at large there are substantial numbers of teenagers with serious disordered eating.”
Swanson SA, Crow SJ, Le Grange D, Swendsen J, & Merikangas KR (2011). Prevalence and Correlates of Eating Disorders in Adolescents: Results From the National Comorbidity Survey Replication Adolescent Supplement. Archives of general psychiatry PMID: 21383252