Demystifying the Genetic and Environmental Influences on Disordered Eating

Genetics play an important role in the development of eating disorders and disordered eating behaviours. To date, many (over 30!) twin studies have been done and all but two found significant genetic effects on the development of eating disorders and disordered eating. However, no methodology is without limitations and tentative conclusions become more convincing when the findings are confirmed using different experimental approaches.

Twin studies, while they offer many advantages, are not that good when it comes to detecting shared environmental effects on a particular trait (literally, evens that happen to both twins and affect them in the same way). Fortunately, twin studies are just one of several different ways that researchers can use to study heritability(A quick reminderHeritability measures the amount of the variability in an observable trait/behaviour that can be attributed to genetic variation. This is NOT the same as … Continue reading →

Beyond Simple Solutions: The Need for Complex Ideas in Anorexia Nervosa

I often hesitate to make broad, sweeping claims about the nature, cause, and experience of eating disorders and disordered eating. However, if there is one thing I feel absolutely certain saying about these disorders, it is that they are incredibly complex and multifaceted with no “one-size fits all” solution. So, I was quite excited when I came across a recent article by Michael Strober and Craig Johnson (2012) that explores the complexity of eating disorders and their treatment. Both authors have significant clinical experience treating eating disorders.

This article uses cases studies, literature, and the authors’ collective clinical experience to respond to some of the key controversies surrounding anorexia and its treatment. Among the major controversies that have come to light of late, they focus on two:

  1. Genetic/biological causation (Biologically-based mental illness – BBMI)
  2. Family-based treatment (FBT) as the best form of treatment for adolescents

The authors’ exploration of these … Continue reading →

The Genetics of Thin-Ideal Internalization

The Tripartite Model of body image dissatisfaction postulates that three factors (peers, parents, and media) affect body image dissatisfaction and disordered eating through thin-ideal internalization and appearance comparison.

Thin-ideal internalization is the extent to which one accepts or “buys into” socioculturally defined beauty standards of thinness. The idea is that the more someone internalizes these standards, the more likely they are to engage in behaviours to achieve their “ideal”, and the more likely they are to develop an eating disorder.

A growing number of of studies have been done evaluating the validity of this model. Although I’m not well-read on the subject, it does seem like there is a growing number of studies showing an association between thin-ideal internalization and disordered eating practices.

But is the picture complete? Are peers, parents, and media the only or even the main factors that influence the extent of … Continue reading →

Demystifying the Genetics of Eating Disorders – Part I

Today I thought I’d take the time to do an overview of what researchers know about the genetics of eating disorders and try to clear up some common misconceptions. The bulk of the content in this blog post comes from a very nice review paper published in 2011 by Drs. Stephanie Zerwas and Cynthia Bulik on the genetics and epigenetics of eating disorders. In an effort to keep blog posts short, this will be a multi-part mini-series.

When it comes to the genetics of eating disorders, there are two main questions that research ask: What is the relative contribution of genetic factors to eating disorder behaviours? And what are those genetic factors? I’ll talk about research attempting to answer the first question in this post and the second question in my next post.

In order to understand the role that genetics plays in influencing eating disorder behaviours, researchers use family, … Continue reading →

Shared Genetics Between Disordered Eating and Periods (Menses)

Puberty at an early age increases the risk for disordered eating behaviours such as bingeing and purging (Jacobi et al., 2004; Kaltiala-Heino et al., 2001). What’s more, the hormone estradiol moderates the risk of disordered eating behaviours. More precisely, in a group of twins with low estradiol levels, differences in disordered eating are likely due to environmental factors (such as family, school, friends), but in a group of twins with high estradiol levels, the differences in disordered eating are more likely due to genetic factors. (I blogged about it here.)

Essentially, estradiol partially moderates the extent to which genes affect disordered eating.

This is interesting because the estrogen system has a role in regulating body weight and food intake, influences eating behaviours during the menstrual cycle, and obviously plays an important role during puberty. Moreover, one study showed that estrogen receptor genes (proteins that bind estrogen) are … Continue reading →