Scientists are studying twins to understand a type of eating disorder linked to anxiety. It could be genetic.

• Avoidant Restrictive Food Intake Disorder (ARFID) is an eating disorder tied to autism and anxiety.
• People with ARFID have trouble eating due to sensory aversions to food.

Researchers have turned to identical and fraternal twins to learn more about an eating disorder that chiefly affects people with autism, as well as people with anxiety.

Avoidant Restrictive Food Intake Disorder (ARFID) is a relatively new diagnosis characterized by sensory aversions to food or a lack of interest in eating, resulting in stalled growth or weight loss, according to the National Eating Disorder Association.

The disorder was only formally recognized in the Diagnostic and Statistical Manual of Mental Disorders' 5th edition in 2013, and was first included in the International Classification of Diseases, 11th Revision last year.

Like with other eating disorders, people with ARFID limit the amount or types of food they consume. But this disorder is unique in that the restrictive eating pattern has nothing to do with body image, and it can be diagnosed at any weight, Kamryn Eddy, co-director of the Eating Disorders Clinical and Research Program at Massachusetts General Hospital, told Insider.

Now, researchers in Sweden have discovered that the disorder may be linked to genetics. The researchers published their findings on February 1 in the journal JAMA Psychiatry.

Their study included a total of 682 children with ARFID picked from nearly 17,000 pairs of twins in Sweden. By tracking diagnoses across twin pairs, researchers at Karolinska Institutet were able to determine that 79% of the risk of developing ARFID can be explained by genetics.

A strong food aversion is not simply 'picky eating'

While many eating disorders are driven by a desire to lose weight, food avoidance in ARFID tends to be motivated by sensory sensitivities. This may include strong reactions to taste, texture, smells, or appearance of food; fear of choking or vomiting; or just a general lack of interest in eating, Eddy said.

"ARFID is not a choice, it's not the patient's fault, and it's not simply 'picky eating,'" Eddy told Insider. "These data can help patients, families, and providers to take the condition seriously."

The disorder is different from picky eating in that people don't grow out of it without therapy. Most childhood picky eaters will diversify their food choices with time, but the genetic basis of the condition means it is more deeply ingrained, according to Eddy.

The genetic component for ARFID is notably stronger than that of other eating disorders, the researchers said. In fact, their findings suggest that its heritability is on par with that of autism and ADHD, which are both known risk factors for ARFID, along with anxiety.

Exposure therapy can help people expand their palate

Eddy said she has seen an explosive increase in ARFID research and demand for care in recent years.

"At this point, more people are aware of the diagnosis and we find people are often feeling relieved at having a name for the condition they've been struggling with," she said.

The recommended treatment involves directly challenging food avoidance and restrictive eating through in- and out-of-session exposures, Eddy said. In her experience, she said most patients have been able to improve their diet and wellbeing with specialized cognitive-behavioral therapy.