Science of Eating Disorders
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Anorexia Nervosa: Can We Blame The Season Of Birth?
I bet you are thinking parents. Or media. Or thin models. Nope.
The SoB I am talking about is the season of birth bias (when the SoB pattern in a specific group differs from that of the general population.)
That SoB.
You might have heard that individuals born between the months of June – August (or sometimes March – August) have a higher chance of developing anorexia nervosa. But is it true? A lot of studies have been done to investigate the question of whether a season of birth (or a month) correlates with a higher risk of anorexia or bulimia nervosa. The results are inconsistent, weak, and fraught with methodological problems.
But first, how could seasons (or the average temperature during birth, or conception) have an effect on the etiology of eating disorders? What’s the hypothesis?
I’m going to summarize some of the studies published on this topic, just to give you an idea of where the field is with regard to this question, and then I’ll briefly touch on some of the methodological problems in many …
More on the Problematic EDNOS Category (and Diagnostic Crossover)
I’ve been thinking a lot lately about the eating disorder not otherwise specified (EDNOS) category. ED-NOS is a diagnostic category for all individuals with subthreshold anorexia or bulimia nervosa or those with a mix of symptoms that don’t fit neatly into AN or BN. ED-NOS is essentially everything else. A mixed bag, if you will. It doesn’t tell the clinician nor the researcher anything useful, outside of what it isn’t. So, is there any use for it? If it doesn’t tell the clinician about patient symptoms or guide choice of treatment, why even bother? Does it help researchers understand EDs or do they just want to avoid this messy and heterogenous group (that by the way makes up most of those with eating disorders)? In this entry (and many more to come), I want to further explore these questions.
There’s been a push by researchers to minimize the amount of people who fall into this category. This has namely been done by loosening the criteria for anorexia and bulimia diagnoses for the next edition of the Diagnostic and …
A Case Against Eating Disorder Not Otherwise Specified (EDNOS)
This study is a follow up on the previous study (last entry) which examined the problems with the EDNOS classification, the frequency of transitions between eating disorders and how the DSM should be changed to reflect the clinical reality of eating disorders (and what is the clinical reality?)
In this study, Eddy and colleagues followed 246 women who were initially diagnosed with either AN or BN, for an average of 9 years. The main goal was to study the growing disparity between (1) the consensus that eating disorders are not stable overtime and how (2) the current diagnostic criteria which do not adequately address this, by following the clinical presentation of EDs overtime and providing suggestions for the upcoming DSM-V.
EDNOS is an often ignored category in research – in main part because it is difficult to study such a heterogeneous group. Nonetheless, Eddy et al summarize some interesting findings on diagnostic crossovers and subthreshold EDs:
- No substantial differences between full-blown and subthreshold (EDNOS) syndromes
- Majority of EDNOS patients have a history of a full-syndrome (82%, Herzog et al
…
The Instability of Eating Disorder Diagnoses
Eating disorders are rarely static. Symptoms fluctuate, waxing and waning as circumstances change. Often, these fluctuations lead to diagnostic crossover – between subtypes of one disorder or to a different eating disorder altogether. The heterogeneity of symptom severity and frequency led to the establishment of the “eating disorder not otherwise specified” diagnosis in the Diagnostic and Statistical Manual. Essentially, it is everything that doesn’t quite fit into the “anorexia nervosa” or “bulimia nervosa” categories. (For example, I would guess that it is a common diagnosis for patients who fail to meet the “amenorrhea” criterion for the AN diagnosis.)
ED-NOS is a category for everything that doesn’t conform to some rather arbitrary criteria required for bulimia nervosa and anorexia nervosa, meaning: it is the diagnosis for a lot of people. Okay, that’s not very scientific, I know, but I wouldn’t trust these numbers anyway – usually people who fall into this category don’t feel “sick enough” to seek treatment, in the USA they have difficulty getting treatment coverage, and many just don’t think they have a problem (and nor do those …
Science of Eating Disorders by Tetyana Pekar is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License.
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