No scientist agreed to establish the cause of anorexia nervosa beyond considering it a mixture of psychic and social factors. At most, they could even suppose that there could be a genetic predisposition behind this pathology, which is defined not only as a serious self-induced weight loss , but also as a mental disorder characterized by the fear of gaining weight, and by a strong feeling of self-rejection (in addition to other behaviors).
But a global study has just been published that can change health professionals’ conception of anorexia nervosa forever, as well as their methods of diagnosis and treatment: the study says that anorexia nervosa is caused in part by a disorder metabolic, and not purely psychiatric, as we believed until now. The research has been led by researchers at King’s College London and the University of North Carolina at Chapel Hill and published in the journal Nature Genetics .
The large-scale study, conducted by more than 100 academics from around the world, identified eight genetic variants linked to anorexia nervosa. The results suggest that the genetic origins of the disorder are both metabolic and psychiatric.
The main findings of the study can be summarized in the following points:
- The genetic basis of anorexia nervosa overlaps with metabolic traits (including glycemic), lipids (fats), and anthropometrics (body measurements), and the study shows that this is independent of genetic effects that influence the rate of body mass (BMI)
- The genetic basis of anorexia nervosa overlaps with other psychiatric disorders, such as obsessive-compulsive disorder, depression, anxiety, and schizophrenia.
- Genetic factors associated with anorexia nervosa also influence physical activity, which could explain the tendency of people with anorexia nervosa to be highly active.
These findings can help to understand, for example, why some people with anorexia nervosa revert to dangerously low weights, even after inpatient rehabilitation.
Dr. Gerome Breen of the Maudsley Center for Biomedical Research at the National Institute for Health Research (NIHR) and the Institute of Psychiatry, Psychology and Neuroscience at King’s College London, who was one of the leaders of the The study said about the results: “The metabolic abnormalities seen in patients with anorexia nervosa are most often attributed to starvation, but our study shows that metabolic differences may also contribute to the development of the disorder.
Furthermore, our analyzes indicate that metabolic factors may play almost as important a role as purely psychiatric effects . “
For her part, Professor Janet Treasure, also from the Institute of Psychiatry, Psychology and Neuroscience at King’s College London, commented as follows: “Over time, there has been uncertainty about the structure of anorexia nervosa due to the combination of characteristics “Physical and psychiatric. Our results confirm this duality and suggest that the integration of metabolic information can help clinicians develop better ways to treat eating disorders .”
A redefinition of anorexia
The study concludes that anorexia nervosa should be viewed as a hybrid “metabolic-psychiatric disorder” and that risk factors, both metabolic and psychological, will be important to consider when exploring new avenues to treat this life-threatening disease.
X-ray of anorexia nervosa
Anorexia nervosa is a serious and life-threatening disease. Symptoms of anorexia can include dangerously low body weight, an intense fear of gaining weight, and a distorted body image. Anorexia nervosa affects 1 to 2% of women and 0.2 to 0.4% of men and has the highest mortality rate of all psychiatric illnesses.
Anorexia nervosa was described for the first time in 1873, although it did not begin to be diagnosed with some frequency until the 1970s . This fact points to the psychosocial causes of anorexia, which would refer to the rise of the media and the proliferation of images of women with a specific body canon (thin and slender). But this conclusion can be tricky, since it could simply coincide with greater use of health services, or greater visibility of the disorder itself, which would cause more people to come to be diagnosed.
According to the health information portal Onmeda.es, the global incidence of anorexia nervosa is between 0.4 and 1.5% of women between 14 and 35 years old, being 10 times more frequent in women than men.
More information:
‘Anorexia Nervosa Genome-wide Association Study Identifies Eight Loci and Implicates Metabo-Psychiatric Origins’, Nature Genetics, DOI: 10.1038 / s41588-019-0439-2
