Anorexia is partly a metabolic disorder and not solely a psychiatric condition, a global study suggested today.
The eating disorder, which is most common in young women, causes sufferers to keep their weight dangerously low by not eating enough or exercising too much, or a combination of both.
Today’s research, involving 100 academics led by researchers at King’s College London, analysed 16,992 cases of anorexia nervosa from 17 countries in Europe, North America and Australasia over 15 years.
It identified eight genetic variants linked to anorexia, including the levels of sugar and “good” cholesterol in the body. These were independent of changes as a patient’s BMI fell. The study, in Nature Genetics, found that genetic factors associated with anorexia also influence physical activity, which could explain the tendency for people with anorexia to be highly active.
Dr Gerome Breen, from the Maudsley Biomedical Research Centre and the Institute of Psychiatry, Psychology & Neuroscience at King’s College, said: “Metabolic abnormalities seen in patients with anorexia nervosa are most often attributed to starvation, but our study shows metabolic differences may also contribute to the development of the disorder. Furthermore, our analyses indicate that the metabolic factors may play nearly, or just as strong a role as purely psychiatric effects.”
Anorexia affects one to two per cent of women and 0.2-0.4 per cent of men and has the highest mortality rate of any psychiatric illness.
The research could lead to the first treatments for anorexia. Dr Breen, the co-author, told the Evening Standard: “I think there is an awful lot of myth-making around the causes of anorexia. It’s not all the environment, it’s not all genetics, and this study shows it’s not all in the brain either. One of the things that is concerning is that there is no approved drug treatment for anorexia. People get given anti-depressants but there is no drug treatment that targets the core symptoms of anorexia.
“That is partly because the patient is very frail when they come to hospital and it may not be good to give them medication, but the treatment of anorexia is almost entirely psychological at the moment. The data seems to suggest that people with anorexia have a genetic tendency to have higher HDL (high-density lipoprotein) cholesterol and be less insulin resistant, or more insulin sensitive.”
Andrew Radford, chief executive of Beat, the eating disorder charity, said: “This is ground-breaking research that significantly increases our understanding of the genetic origins of this serious illness. We strongly encourage researchers to examine the results of this study and consider how it can contribute to the development of new treatments.”
- Dr Breen and colleagues are launching a project in September to recruit people who have experienced anorexia, bulimia or binge-eating disorder: www.edgi.org