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Alcohol dependence and bulimia may share common genetic risk factors

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People who suffer from alcohol addiction may be more vulnerable to certain types of eating disorders – and vice versa.  Now, new research indicates this susceptibility may lie in their genetics.

In a study published in the Journal of Studies on Alcohol and Drugs, researchers found that common genetic factors may underlie both alcoholism and specific symptoms of eating disorders – most notably, the binge eating and purging habits associated with bulimia nervosa.  

“Prior studies have shown that among people who had eating disorders, there were higher rates of alcohol abuse and dependence than those who didn’t have these eating disorders,” study author Melissa Munn-Chernoff, of Washington University School of Medicine in St. Louis, told FoxNews.com.  “…Also, studies had found higher rates of alcohol dependence in bulimia nervosa than anorexia nervosa.”

Although past research has shown a connection between the two disorders, it was never clear whether genetics could explain the association.

To better understand the underlying link, Munn-Chernoff and her team analyzed data from nearly 6,000 adult Australian twins– both identical and fraternal.  Identical twins share all of their same genes, while fraternal twins only share about half, making them genetically similar to siblings who aren’t twins. Munn-Chernoff explained that studying both types of twins helps researchers better distinguish whether conditions are more a product of genes or of the environment.  

“Doing these types of studies is a necessary first step, because if they don’t show the traits are heritable, then we wouldn’t need to study the genes directly,” Munn-Chernoff explained.  “..If identical twins are more similar to these behaviors than the fraternal twins, this would suggest that genes would be more important than environment.”

The researchers conducted a series of diagnostic interviews to determine the participants’ alcohol and eating habits. The found that nearly 25 percent of men and 6 percent of women studied had been alcohol dependent at some point in their lives, and 11 percent of men and 13 percent of women had experienced problems with binge eating.  Additionally, 14 percent of women admitted to using two or more purging tactics. Men were not asked about their purging histories.

After comparing the twins to one another, they found that genetics seemed to play a crucial role in the development of any of the three disorders, explaining 38 percent to 53 percent of a person’s risk.  Furthermore, the same genetic risk factors for alcoholism seemed to make people susceptible to binging and purging as well.

Though genetics seem to play an important role in these disorders, Munn-Chernoff noted that a person’s environment still influences a person’s risk for alcoholism or bulimia.

“These types of studies capture the nature and nurture debate,” she said.  “It’s always a combination of both, but these studies are designed to tap into that, and even though we didn’t find significant environmental risk factors, it doesn’t mean that they’re not important.”

Because the two disorders may share a common genetic link, Munn-Chernoff wants to expand her research to determine exactly which genes are involved in disease development.  But in the meantime, she hopes her findings will encourage physicians to associate alcoholism with bulimia, assuming that the two fit together.  She advised that if a patient presents with symptoms for one disorder, his or her doctor should ask them about potential symptoms for the other disorder.

“These two behaviors do occur together, not just in women but also in men,” Munn-Chernoff said.  “…They could be linked for many different reasons.  All forms of psychopathology share some kind of genetic component, and these two behaviors have not been looked at together as often as they should be.”