Eating Disorders: Nature AND Nurture

Published: March 11, 2014

In psychiatry and psychology, the nature versus nurture debate is a classic. In essence, this discussion relates to the importance of an individual’s innate qualities (i.e., nature) as compared with their personal experiences (i.e., nurture) in causing differences in traits (e.g., eating disorder diagnosis). Sometimes nurture is thought to just relate to how one is raised by his or her parents, but it really entails any personal experience. For the purposes of this blog, nature refers to heredity/genes whereas nurture refers to environment.

National Eating Disorder Awareness Week brought a lot of attention to eating disorders in February in the news, social media, and the Internet. In many stories, the nature-nurture debate seemed to arise such that the conversations in the media seem to sort into two camps—those who talk about the biological/genetic influences on eating disorders and those who talk about the societal and cultural influences on eating disorder development. When one or the other gets brought up, the other camp sometimes interjects, “Wait don’t forget about us” or when a research study is mentioned that focuses primarily on one of these two areas, there is often a comment asking if this study is implying this [genes or society] is the sole cause of eating disorders. Readers seem to miss that many of us clearly discuss both genes and environment. Readers and listeners seem to gravitate to  “either/or” thinking. If someone focuses on environment, listeners fear that we are trivializing eating disorders as choices or vanity. If someone focuses on genes, then the fear arises that it is genetic “destiny” that paves the way for an eating disorder.large__7445337412

Although my research falls more into the biological/genetic camp, that does not mean that I don’t recognize the role of society, culture, and media in eating disorder risk. Listening to these either/or commentaries during National Eating Disorders Awareness Week inspired me to write this blog to spread the word that the working hypothesis in regard to the cause of eating disorders is that genetic and environmental (e.g., society, culture) factors work together to influence risk for eating disorders.

Although considerable research has established that eating disorders have a genetic component, these genetic factors do not account for 100% of the liability to the disorders. For example, individuals who have a family member with an eating disorder are up to 11-times more likely to develop an eating disorder themselves and approximately 40-60% of the risk for anorexia nervosa, bulimia nervosa, and binge eating disorder are accounted for by genetic factors.1 However, not everyone with a family history of an eating disorder develops an eating disorder. And people with no known family history of eating disorders, may develop one his or herself. So clearly other factors are involved. Additionally, research has shown that when a culture is exposure to Westernized media, eating disorder symptoms increase,2 and exposure to social media can influence eating disorder symptoms.3 Importantly, however, not every girl (or boy) who grows up in our society develops an eating disorder. Thus, these genetic and cultural factors work together to increase risk.

One sure-way in which genes and environment co-act is that people’s genetic predisposition may influence what types of environments they expose themselves to. For example, an individual’s genetically influenced trait (e.g., personality) may influence whether she or he takes up sports that tend to be highly weight focused (e.g., gymnastics, wrestling). Someone who is very detail oriented and persistent might gravitate toward ballet rather than soccer.

A second way that genes and environment co-act is that an individuals genetically influenced traits might influence how they respond to an environmental stressor. Although many young men might get focused on their body fat, only the one who is more genetically predisposed might find that that focus slips into a frank eating disorder.

So how does saying an eating disorder has a genetic or societal component influence the way we view eating disorders? Well, a handful of studies have examined the perceptions of mental illness in those with a mental illness and of those without based on differing vignettes (i.e., a brief account of a patient’s disorder). One such study compared university students’ attitudes toward individuals with anorexia, bulimia, binge eating disorder, obesity, and major depression.4 The university students blamed individuals with eating disorders more for their disorder than individuals with major depression—suggesting that the public may perceive eating disorders as more “controllable” than other mental illnesses. Another study interviewed women with a current or past history of an eating disorder and provided them with either genetic or non-genetic explanations for the cause of eating disorders.5 Results found that most individuals expected genetic explanations to reduce the stigma of having an eating disorder. They believed genetic explanations would reduce the perception that eating disorders are controllable or a choice (as was suggested in the previously mentioned study). When college students were presented with vignettes about individuals with an eating disorder and provided either a biological or societal explanation for the disorder, vignettes depicting individuals with a biological etiology were rated as least responsible for their disorder, least self-destructive, and least likely to recover. Individuals depicted by sociocultural etiologies were rated by students as more responsible for their condition, more self-destructive, and more likely to recover.6 These findings highlight the need for increased education and knowledge about the etiology of eating disorders as clearly solely biological and solely cultural explanations come at a cost.

Another question I am commonly asked is, “Ok, so genes are involved, but how can that help prevention and treatment?” Actually, a lot! Although eating disorder prevention is complicated, genetic information can assist. We already know that eating disorders are familial, so special vigilance to offspring of individuals who have had eating disorders may be a logical targeted approach to prevention (although this would not catch those sporadic cases). Additionally, this type of information could be used to predict who would benefit from pharmacological treatment. Psychiatric medications are often used as part of eating disorder treatment, yet there is not a clear and consistent beneficial impact of these medications for everyone. This may be in part due to the fact an individual’s genetic makeup affects how he or she will respond to medication. For example, this could provide us important information about medication dosages needed to observe a therapeutic effect as well as which “types” of medication may be helpful for specific people (i.e., SSRI versus MAOI antidepressant medication). Thus, in the distant future, with sufficient progress in genetics, we may gain knowledge about who will benefit from psychiatric medications (and which type) and who will not.

So eating disorders are not caused 100% by genes or 100% by society/culture. The working hypothesis is that genes and environment co-act to influence risk—like a “perfect storm.” Just the right genetic predisposition put in just the right environment/society at the right point in development can set the stage for an eating disorder. As Dr. Bulik has said on many occasions,  “Genes load the gun, environment pulls the trigger.” In order to fully determine the factors that lead to the development of eating disorders the nature versus nurture debate needs to change focus to nature AND nurture. Pigeonholing eating disorders as purely genetic and purely societal has negative stigma costs for those suffering. We need to work toward an appreciation of the complex ways in which genes and environment co-act to influence risk.

1.         Trace SE, Baker JH, Penas-Lledo E, Bulik CM. The genetics of eating disorders. Annual Review of Clinical Psychology. 2013;9:589-620.

2.         Becker A, Burwell R, Gilman S, Herzog D, Hamburg P. Eating behaviours and attitudes following prolonged exposure to television among ethnic Fijian adolescent girls. British Journal of Psychiatry. 2002;180:509-514.

3.         Becker AE, Fay KE, Agnew-Blais J, Khan AN, Striegel-Moore RH, Gilman SE. Social network media exposure and adolescent eating pathology in Fiji. The British Journal of Psychiatry. 2011;198(1):43-50.

4.         Ebneter DS, Latner JD. Stigmatizing attitudes differ across mental health disorders: a comparison of stigma across eating disorders, obesity, and major depressive disorder. The Journal of Nervous and Mental Disease. 2013;201(4):281-285.

5.         Easter MM. “Not all my fault”: genetics, stigma, and personal responsibility for women with eating disorders. Social Science & Medicine. 2012;75(8):1408-1416.

6.         Wingfield N, Kelly N, Serdar K, Shivy VA, Mazzeo SE. College students’ perceptions of individuals with anorexia and bulimia nervosa. The International Journal of Eating Disorders. 2011;44(4):369-375.

photo credit: Matt Batchelor via Creative Commons 

photo credit: gemmerich via Creative Commons