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March 20, 2017

Genetic Factors Behind Eating Disorders

Brain Reward Response on Anorexia

The genetic factors behind eating disorders may not be predictive of an eating disorder, but can contribute to the onset of a disorder. In some individuals with eating disorders, certain identified chemicals in the brain that control hunger, appetite, and digestion have been found to be unbalanced [1].

Family, twin, and adoption studies have shown compelling evidence that genetic factors contribute to a predisposition for eating disorders [2]. Those that are born with specific genotypes are at a heightened risk for the development of an eating disorder. Those who have a family member with an eating disorder, are 7-12 [2] times more likely to develop an eating disorder.

Genes Connected to Personality Traits

Some genes identified in the contribution to eating disorders have been shown to be associated with specific personality traits. They are believed to be highly heritable and often exist prior to the onset of the eating disorder. These traits are:

  • Obsessive thinking
  • Perfectionistic tendencies
  • Sensitivity to reward and punishment
  • Emotional instability
  • Hypersensitivity
  • Impulsivity
  • Rigidity [2].

Genetic Factors Behind Eating Disorders must take into consideration families. Family studies of those with anorexia and bulimia have found a higher lifetime prevalence of eating disorders among relatives of eating Research testdisorders [3, 4].

Twin studies also suggest that both anorexia and bulimia are significantly influenced by genetic factors. When looking at the differences between identical and fraternal twins, correlations are two times greater in identical twins of eating disorders [5].

An Overview of Genetic Research

A study by the Michigan State University found that there are genetic risk factors for the development of eating disorders [5]. This study looked at 500 14-year-old twin females and found that prior to puberty, environmental factors were the link to the development of eating disorders, but after puberty, there is a 50% genetic reason for eating disorder emergence.

In 1996 a private European foundation, Price Foundation, funded research into the genetic influence of eating disorders [7]. The team looked at 600 families with two or more members who had anorexia or bulimia, and then looked at an additional 700 families with 3 more members who had anorexia or bulimia and compared to a control group of 700 women.

Research results showed results of possible Chromosome 1 and 10 that appear to be significantly linked to anorexia and bulimia. Follow up studies of candidate genes have also identified several genes that may increase an individual’s vulnerability to eating disorders.

Scientists from the University of Iowa and University of Texas Southwestern Medical Center looked at single families where eating disorders were common across generations [8]. The study found that individuals with mutations in two genes, the ESRRA and HDAC4 had a 90% and 85% chance of developing an eating disorder.

Researchers believe that the pathway where the genes were found, works to increase a person’s desire for food when they have an increased need for calories, but when the genes are mutated, they can block a person’s ability to want to eat. In addition to the study finding two gene mutations, it also found that those who had the mutations did not show signs of an eating disorder when they were very young [8].

Eating Disorders as a Biological Illness

According to the Mayo Clinic, they report that these findings are able to help researchers, medical providers, therapists, and treatment teams to see eating disorders as a biological illness, where individuals share temperament predispositions. Still, researchers feel that there are environmental factors in the role of the development of an eating disorder, up to 50-70% is genetic, while 30-50% is environmental.

In a Canadian Study on anorexia, it was found that those who struggle with anorexia over a long period of time, a person’s brain changes how one’s genes are expressed, otherwise known as epigenetics. It works by a process called methylation where the level of methylation of a gene determines whether the gene is turned off or not [9].

According to Howard Steiger, a researcher on the study states that eating disorders are known to have a tendency to become more entrenched over time, and these findings point to physical mechanisms acting upon physiological and nervous system functions throughout the body.

ResearchIn a further study by the Washington University School of Medicine in St. Louis, researchers found that eating disorders and alcohol dependence may share some of the same genes [10]. Data gathered from 6,000 adult twins in Australia, it was found that common genetic factors underlie alcoholism and certain eating disorder symptoms, such as binge eating and purging habits that include self-induced vomiting and the abuse of laxatives.

These findings show that identical twins share 100% of their genetic makeup, while fraternal twins share about half. When comparing identical to fraternal, researchers can develop estimates of how much is due to genes versus environment.

In conclusion, genetic factors behind eating disorders is a complex one that needs further study and advancement. Genetic factors can play a role in the development and onset of eating disorders but do not define 100% the causality of an eating disorder.

 


Image of Libby Lyons and familyAbout the Author: Libby Lyons, MSW, LCSW, CEDS is a specialist in the eating disorder field. Libby has been treating eating disorders for 10 years within the St. Louis area, and enjoys working with individuals of all ages.


References:

[1] https://www.nationaleatingdisorders.org/factors-may-contribute-eating-disorders
[2] https://eatingdisorder.org/eating-disorder-information/underlying-causes/
[3] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2719561/
[4]https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3010958/
[6]https://www.sciencedaily.com/releases/2007/05/070511150158.htm
[7]http://www.webmd.com/mental-health/eating-disorders/anorexia-nervosa/features/anorexia-bulimia-genetic-code#1
[8] https://www.usnews.com/news/articles/2013/10/08/researchers-find-genes-linked-to-high-risk-of-eating-disorders
[9] https://www.geneticliteracyproject.org/2015/02/23/you-are-what-you-dont-eat-genetics-of-anorexia-and-bulimia-nervosa/
[10] https://source.wustl.edu/2013/08/alcohol-abuse-eating-disorders-share-genetic-link/


The opinions and views of our guest contributors are shared to provide a broad perspective of eating disorders. These are not necessarily the views of Eating Disorder Hope, but an effort to offer discussion of various issues by different concerned individuals.

We at Eating Disorder Hope understand that eating disorders result from a combination of environmental and genetic factors. If you or a loved one are suffering from an eating disorder, please know that there is hope for you, and seek immediate professional help.

Reviewed By: Jacquelyn Ekern, MS, LPC on March 19, 2017.
Published on EatingDisorderHope.com

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