People suffering from this condition tend to restrict the foods they eat due to sensory aversion to certain tastes, smells and textures as well as traumatic food experiences.
It is estimated that 1-5% of the world’s population suffers from an eating disorder that few people even know exists. Known as Restrictive Eating Disorderor Arfid (due to its meaning in English, Avoidant Restrictive Food Intake Disorder), the condition is a extreme form of restrictive feeding — which, if left unchecked, can have a severe impact on life and health of a person.
Despite Arfid’s gravity, very little is known yet about its causes — which hinders the development of effective treatments. But in Arfid’s first study of twin brothers, the team has now revealed that genetic factors play an important role in their development.
This investigation brings us closer to understanding of the causes of Arfid — and has given scientists hope that one day it will find best ways to treat the disease.
Arfid was first defined as an eating disorder in 2013. People with the condition consume a extremely limited variety of food or too little food (or both). But compared to people with other eating disorders — such as anorexia nervosa — this dietary restriction is not motivated by body dissatisfaction or by the desire to lose weight.
Instead, people restrict the foods they usually eat due to sensory aversion to certain tastes, smells and textureslow appetite, as well as traumatic eating experiences — such as choking on food and fear of gastrointestinal pain. This restriction is so extreme that it leads to weight loss, vitamin and mineral deficienciesand can affect a person’s daily life.
Arfid affects so many men like womenwhile other eating disorders — such as anorexia nervosa and bulimia nervosa — occur more frequently in girls and women. Also, unlike other eating disorders, Arfid usually develops in the early childhood.
twins and genetics
It is known that other eating disorders are moderately to highly influenced by genetics of a person. It is therefore highly likely that genetic factors may also partly explain why some people develop Arfid and others not.
As such, scientists have dedicated themselves to studying the extent to which “heredity” — a complex concept that measures the proportion by which differences in people’s characteristics are explained by differences in their genes — has influence.
To estimate the heritability of any trait, you can use the method of the twins. This makes use of the fact that identical twins share all their genes, while non-identical twins share on average 50% of the genes that make different people each other.
Furthermore, as the twins grow in the same environment and exactly to Same timewe can exclude that the influences of this shared environment cause any differences between them (as can happen with common siblings of different ages).
As such, researchers compared the similarity of a certain characteristic between identical twins with their similarity between non-identical twins. The degree of similarity between identical twins gives a estimate of heredity of this feature.
In order to estimate Arfid’s heritability, scientists started by consulting data from the Swedish Twin Registry, which tracked the health of 34,000 twins. First, combined data of parental questionnaires and recorded clinical diagnoses to identify children with Arfid. They then applied the twins method, verifying that the arfid’s heredity was from 70-85%. This means that whether or not the children had Arfid was between 70-85% explained by differences in their genes.
This puts Arfid among the mental disorder with a more hereditary component strong. In comparison, the heritability of autism is estimated to be 79-84% and that of ADHD is 76-89%. Furthermore, Arfid’s heredity is higher than anorexia nervous (48-74%), nervous bulimia (55-61%), and the edible disorder (39-57%), suggesting that Arfid may be the most heritable of eating disorders.
hope of treatments
Discoveries like this can help reduce stigma and blame around mental disorders like Arfid and other eating disorders. An person does not choose for developing Arfid — and similarly, one parent doesn’t get their child to develop.
However, the fact that Arfid’s heredity is less than 100% also shows that no it’s just the genes that cause someone to develop the disorder. Other factors, such as the suffocation very serious food or reactions Severe allergies can trigger the development of this eating disorder.
The findings also suggest that genetic studies have an epotential norm to help us understand the causes of Arfid. This is what our next study will aim to do.
At the moment, they are being developed treatments for Arfid using cognitive behavioral therapy and family-based therapy. However, these methods usually focus on the symptoms rather than the underlying causes of the eating disorder.
We still don’t know either how these treatments work well. But a better understanding of the causes of Arfid, including its underlying biology, will help us to develop better treatments.
