Anorexia Nervosa is a serious mental illness characterised by restricted calorie intake, low body mass, intense fear of gaining weight and distorted body image. It affects between 1% and 4% of women and about 0.3% of men.
Although a strong genetic component has long been understood, new research into the eating disorder suggests that a predisposition is also part metabolic, not purely psychiatric as previously thought.
The global study, published in Nature Genetics was led by researchers at King’s College London and University of North Carolina at Chapel Hill. It identified—for the first time—eight specific genes associated with an increased risk of developing anorexia nervosa and found unexpected links between metabolism and the disorder.
Researchers looked at 16,992 people with anorexia and 55,525 people without the disease in 17 countries across North America, Europe and Australasia and discovered genetic mutations common amongst anorexia patients, including some that control the body’s metabolism and processing of sugars and fats.
“There is something in those systems that has gone awry,” professor Janet Treasure, from the Institute of Psychiatry, Psychology & Neuroscience at King’s College London, told BBC News.
Although the exact role this plays is still inconclusive, it is understood that these suspected mutations allow people to starve their bodies for longer. When regular weight loss occurs, signals in the body push back to stimulate appetite, a mechanism that’s said to be altered in anorexia sufferers.
These are very important in controlling the set-point of weight, explains Professor Treasure. “It’s possible that when people lose weight with anorexia nervosa, they haven’t got such strong drivers getting the set-point back to normal.”
“Over time there has been uncertainty about the framing of anorexia nervosa because of the mixture of physical and psychiatric features. Our results confirm this duality and suggest that integrating metabolic information may help clinicians to develop better ways to treat eating disorders.”
The study concludes that anorexia nervosa may need to be thought of as a hybrid ‘metabo-psychiatric disorder’ and the findings have been described as groundbreaking when it comes to further exploring the genesis of anorexia nervosa and what the link to metabolism means for future studies in this area.