A new large-scale genome-wide association study published in Nature Genetics, has identified eight genetic variants significantly associated with anorexia nervosa; and the research shows that the origins of this serious disorder appear to be both metabolic and psychiatric.
Anorexia nervosa is a life-impairing illness characterized by dangerously low body weight, an intense fear of gaining weight, and a lack of recognition of the seriousness of the low body weight.
Anorexia nervosa has the highest mortality rate of any psychiatric illness, according to the National Center of Excellence for Eating Disorders.
“Until now, our focus has been on the psychological aspects of anorexia nervosa such as the patients’ drive for thinness.
Our findings strongly encourage us to also shine the torch on the role of metabolism to help understand why individuals with anorexia frequently drop back to dangerously low weights, even after therapeutic renourishment.
A failure to consider the role of metabolism may have contributed to the poor track record among health professionals in treating this illness,” said principal investigator Cynthia M. Bulik, PhD, FAED, founding director of the UNC Center of Excellence for Eating Disorders and Distinguished Professor in the Department of Psychiatry in the UNC School of Medicine.
The genetic basis of anorexia nervosa overlaps with other psychiatric disorders such as obsessive-compulsive disorder, depression, anxiety, and schizophrenia. The image is in the public domain.
For the study, Bulik and a multinational group of more than 100 researchers combined data collected by the Anorexia Nervosa Genetics Initiative (ANGI) and the Eating Disorders Working Group of the Psychiatric Genomics Consortium (PGC-ED). The resulting data set included 16,992 anorexia nervosa cases and 55,525 controls of Eur
opean ancestry from 17 countries across North America, Europe, and Australasia.
Other findings of the study include:
- 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 help explain the tendency for people with anorexia nervosa to be highly active.
- Intriguingly, the genetic basis of anorexia nervosa overlaps with metabolic (including glycemic), lipid (fats), and anthropometric (body measurement) traits, and the study shows that this is not due to genetic effects that influence BMI.
Dr. Gerome Breen of King’s College London, who co-led the study said, “Metabolic abnormalities seen in patients with anorexia nervosa are most often attributed to starvation, but this study shows they may also contribute to the development of the disorder.
These results suggest that genetic studies of eating disorders may yield powerful new clues about their causes and may change how we approach and treat anorexia.”
The study concludes that anorexia nervosa may be a ‘metabo-psychiatric disorder’ and that it will be important to consider both metabolic and psychological risk factors when exploring new avenues for treating this potentially lethal illness.
Researchers from over 100 institutions worldwide participated in the study.
The Anorexia Nervosa Genetics Initiative (ANGI) is an initiative of The Klarman Family Foundation.
ANGI was led by Dr. Bulik at the University of North Carolina at Chapel Hill with collaborators from Karolinska Institutet, Stockholm, Sweden (Dr. Mikael Landén), Aarhus University, Aarhus, Denmark (Dr. Preben Bo Mortensen), and Berghofer Queensland Institute for Medical Research, Brisbane, Australia (Dr. Nick Martin) with assistance from the University of Otago, Christchurch New Zealand (Drs. Martin Kennedy and Jenny Jordan). ANGI contributed 13,363 cases to the GWAS. Drs. Bulik and Breen co-chair the Eating Disorders Working Group of the Psychiatric Genomics Consortium (PGC-ED), which contributed the second largest number of samples and is expanding these studies to include other eating disorders as well.
Funding: Funding was provided by The Klarman Family Foundation, the U.S. National Institute of Mental Health, the UK National Institute for Health Research, and the Foundation of Hope, Raleigh, NC.
Major Types of Anorexia
There are two common types of anorexia, which are as follows:
- Binge/Purge Type – The person struggling with this type of eating disorder will often purge after eating. This alleviates the fear of gaining weight and offsets some of the guilt of having ingested forbidden, or highly restricted food. The compensatory purge behavior by the individual with Binge/Purge Type anorexia may purge by exercising excessively, vomiting or abusing laxatives.
- Restrictive – The individual suffering from restrictive anorexia is often perceived as highly self-disciplined. They restrict the quantity of food, calories and often high fat or high sugar foods. They consume far fewer calories than are needed to maintain a healthy weight. This is a heartbreaking form of self-starvation.
Though two classifications of this eating disorder exist, both types exhibit similar symptoms, such as an irrational fear of weight gain and abnormal eating patterns.
Causes of Anorexia
It has been said that genetics load the gun and environment pulls the trigger in eating disorders. This eating disorder is based on genetic predisposition, personality traits, and environmental factors.
Examples of environmental factors that would contribute to the occurrence of this eating disorder are:
- The effects of the thinness culture in media, that constantly reinforce thin people as ideal stereotypes
- Professions and careers that promote being thin and weight loss, such as ballet and modeling
- Family and childhood traumas: childhood sexual abuse, severe trauma
- Peer pressure among friends and co-workers to be thin or be sexy.
Examples of biological factors include:
- Irregular hormone functions
- Genetics (the tie between anorexia and one’s genes is still being heavily researched, but we know that genetics is a part of the story).
Anorexia Signs & Symptoms
An individual suffering from anorexia nervosa may reveal one or several signs and symptoms such as:
- Chronic restrictive eating or dieting, beyond the norm
- Rapidly losing weight or being significantly underweight and emaciated
- Obsession with calories and fat contents of food
- Engaging in ritualistic eating patterns, such as cutting food into tiny pieces, eating alone, and/or hiding food
- Continued fixation with food, recipes, or cooking; the individual may cook intricate meals for others but refrain from partaking
- Amenorrhea: an abnormal absence of menstruation, or loss of 3 consecutive menstrual cycles
- Depression or lethargic stage
- Development of lanugo: soft, fine hair that grows on face and body
- Reported sensation of feeling cold, particularly in extremities
- Loss or thinning of hair
- Avoidance of social functions, family, and friends. May become isolated and withdrawn
Dieting Vs. Anorexia
Though the restrictive eating patterns that characterize this anorexic eating disorder are similar to dieting behaviors, there are stark differences between the two. The effects of the extreme behaviors resulting from this disease are far more devastating and consequential than any ill effects from dieting.
While someone may diet in an attempt to control weight, anorexia nervosa is often an attempt to gain control over one’s life and emotions, especially in the light of traumatic events or a chaotic environment.
While someone might diet in an attempt to lose weight as the primary goal, in anorexia they may diet because they perceive losing weight as a way to achieve happiness and self-mastery.
Seeking anorexia recovery from a well-qualified team of eating disorder specialists, consisting of a therapist, physician and nutritionist are recommended. Effective, holistic eating disorder treatment of anorexia involves three necessary components:
- Medical: The highest priority in the treatment of anorexia nervosa is addressing any serious health issues that may have resulted from the eating disordered behaviors, such as malnutrition, electrolyte imbalance, amenorrhea and an unstable heartbeat.
- Nutritional: This component encompasses weight restoration, implementation and supervision of a tailored meal plan, and education about normal eating patterns.
- Therapy: The goal of this part of treatment is to recognize underlying issues associated with the eating disorder, address and heal from traumatic life events, learn healthier coping skills and further develop the capacity to express and deal with emotions.
University of North Carolina Health Care
Carleigh Gabryel – University of North Carolina Health Care
The image is in the public domain.
Original Research: Open access
“Genome-wide association study identifies eight risk loci and implicates metabo-psychiatric origins for anorexia nervosa”. Cynthia M. Bulik et al.
Nature Genetics. doi:10.1038/s41588-019-0439-2