New research from the US suggests that having a genetic risk for alcohol dependence may also put people at higher risk for certain eating disorders, and vice versa.
In the September issue of the Journal of Studies on Alcohol and Drugs, researchers at the Washington University School of Medicine in St. Louis report how they discovered that some of the genes that influence alcohol dependence also influence certain eating disorder symptoms in men and women.
Their analysis suggests genes may explain 38-53% of the risk of developing these disorders.
First author Dr. Melissa Munn-Chernoff, a postdoctoral research scholar in psychiatry, says:
"In clinical practice, it's been observed that individuals with eating disorders also have high rates of alcohol abuse and dependence."
She adds that previous research into genetic links between alcohol dependence and eating disorders have tended to study women only, and that their study is the first to include men.
Genetic study using twins
For their analysis, the team used data on nearly 6,000 adult twins in Australia that had taken part in another genetic study also designed to gather information about alcohol use and eating disoder symptoms.
By studying twins they could use stastical tools to find the odds of certain traits coming from the same genes, based on the fact that 100% of genes are the same in identical twins, and about 50% are the same in fraternal twins, as Dr. Munn-Chernoff explains:
"By comparing the findings in identical and fraternal twins, we can develop estimates of how much of the difference in particular traits is due to genes or environment.
We found that some of the genes that influence alcohol dependence also influence binge eating in men and women."
The researchers focused on two main symptoms of eating disorders - binge eating and compensatory behaviors, which include purging (self-induced vomiting, for example), use of laxatives and diuretics - because several studies have already suggested links between these and alcohol dependence.
However, although the study had asked both male and female twins about binge eating, data on compensatory behaviors had only been gathered on the female twins. So the findings for women could have been true of the men too, if they had been asked the same questions.
The results showed that of all the participants:
- Nearly 25% of men and 6% of women had ever been alcohol dependent
- Almost 11% of men and 13% of women had ever had a problem with binge eating, and
- About 14% of women had ever used two or more compensatory tactics such as self-induced vomiting or using laxatives.
But overall, genes appeared to feature significantly in the chance of developing any of the three disorders.
And it seemed that some of the genes linked to alcohol dependence were also linked to binge eating and compensatory behaviors, although the researchers cannot say exactly which genes they were.
They plan to carry on with their work and look at twins from other races (the Australian twins from this study were Caucasian).
Dr. Munn-Chernoff says they would also like to take blood and saliva samples to see if they can pinpoint the actual genes involved.
What do the findings mean in practice?
Health professionals need to be more aware of the links between alcohol dependence and eating disorders, and look for opportunities to treat them at the same time, Dr. Munn-Chernoff says, after explaining that:
"When you go to an eating disorder treatment center, they don't often ask questions about alcoholism. And when you go for alcoholism treatment, they don't generally ask questions about eating disorder symptoms."
In another recent study that looked at traits common to an eating disorder and another condition, UK researchers speculate whether anorexia and autism are linked after discovering girls with anorexia nervosa have some of the traits observed in people with autism.Written by Catharine Paddock PhD