31 Jan Twin Study Finds Rare Avoidant Restrictive Food Intake Disorder Highly Heritable
MedicalResearch.com Interview with:
Lisa Dinkler, Ph.D. | Postdoctoral researcher
Center for Eating Disorders Innovation (CEDI)
Department of Medical Epidemiology and Biostatistics
Karolinska Institutet, Stockholm
MedicalResearch.com: What is the background for this study?
Response: Avoidant restrictive food intake disorder (ARFID) is a relatively recently defined eating disorder. Affected people severely restrict their food intake in terms of total amount or variety. This leads to serious physical, psychological, and social consequences such as weight loss, nutritional deficiencies, and social isolation. Compared to people with other eating disorders – such as anorexia nervosa, bulimia nervosa, and binge-eating disorder – food restriction in people with ARFID is not driven by body dissatisfaction or the desire to lose weight.
Despite how serious ARFID is, we still know very little about what causes it – making it difficult to develop effective treatments. We do know that genetic factors contribute significantly to the development of other eating disorders (so-called heritability), but we did not yet know to which degree genetic factors play a role in the development of ARFID. We therefore conducted the first twin study of ARFID, using a sample of ~34,000 Swedish twins including ~700 children with ARFID.
MedicalResearch.com: What are the main findings?
Response: We found that Avoidant restrictive food intake disorder is highly heritable: whether the children in our sample had ARFID or not was to 70-85% explained by differences in their genes. The genetic component of ARFID is higher than that of other eating disorders and on par with that of neurodevelopmental conditions such as autism and attention deficit hyperactivity disorder (ADHD). However, non-genetic factors that can cause or trigger the onset of ARFID also played a role, as they explained the remaining portion of variation between people.
MedicalResearch.com: What should readers take away from your report?
Response: Our results strongly suggest that twin studies and molecular genetic studies have huge potential to help us understand the biology underlying ARFID. Our finding is also important as the knowledge that mental disorders are strongly influenced by genetic factors can help reduce stigma and blame, which is a huge problem in the field of eating disorders. Our result implies that a person does not choose to develop ARFID, and a parent does not cause their child to develop ARFID. Instead, genetic predisposition is the most important factor, and this genetic predisposition can potentially be triggered by non-genetic factors. Lastly, we need to remember that this is only the first twin study of ARFID, and we will have to see if studies from other samples show similar results.
MedicalResearch.com: What recommendations do you have for future research as a results of this study?
Response: Now we need to go ahead and study the specific genes associated with ARFID to understand their biological pathways. In the end this will help us to develop better treatments. We are currently planning a large genetic study of ARFID in 4-9-year-old Swedish children from whom we will collect saliva for DNA, and parents will fill in questionnaires. Apart from genes associated with ARFID, we will study non-genetic factors that contributed to the development of ARFID, as well as co-occurring mental and somatic disorders, and how these children do in the long-term. We will also collect stool samples to study how microbiota and microbiome are linked to ARFID. So essentially, we will be looking at ARFID from all angles to better understand this serious disorder.
Disclosures: Lisa Dinkler receives funding from the Mental Health Foundation (2022) and the Fredrik and Ingrid Thurings Foundation (2021-00660). Some of the researchers involved in this study have received fees from private companies for work done outside this study, see the scientific article for more information.
Etiology of the broad avoidant restrictive food intake disorder phenotype in Swedish twins aged 6 to 12 years, JAMA Psychiatry (2023). DOI: 10.1001/jamapsychiatry.2022.4612
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