Avoidant/Restrictive Food Intake Disorder and the Brain

When you hear the words “eating disorder," what comes to mind? Anorexia Nervosa (AN)?

Understandable, considering that most of our knowledge about eating disorders comes from popular media, and AN is an "interesting" illness.¹⁴ Moreover, media depictions of AN play into gender stereotypes of young women striving for thinness.

But are you familiar with Avoidant/Restrictive Food Intake Disorder (ARFID), a different, but equally perplexing eating disorder?

Up to 23% of individuals in eating disorders treatment programs display ARFID symptoms,¹ and its prevalence is rising.⁴

What Is ARFID?

ARFID shares core features with AN, including malnourishment and food restriction.² And, while most cases occur in children and adolescents, ARFID can develop across the lifespan.

Where AN and ARFID differ is that ARFID develops without weight and body image concerns. For example, one individual diagnosed with ARFID maintained a rigid diet of pizza, plain pasta, fries, and chicken nuggets.¹⁰

You might then be wondering what causes food restriction/avoidance in ARFID.

When eating becomes unpleasant.

Source: Mikhail Nilov/Pexels

ARFID manifests in response to discomfort during and/or following eating. Specifically, food restriction/avoidance is classified into three types:³

1. Sensory sensitivity (i.e., food texture)
2. Lack of interest in food and/or eating (i.e., homeostatic abnormalities)
3. Fear of aversive food consequences (i.e., gastrointestinal problems)¹²

Dimensional Perspectives

Variations within ARFID subtypes have made research challenging.

Therefore, the best approach we have (so far) for researching ARFID is Thomas et al.’s (2017) Three-Dimensional Model.³ This model permits the co-occurrence of food avoidance subtypes with varying severity.

For example, an individual might show minor disinterest in eating, but major aversions to chewy foods. This dimensional perspective helps clinicians determine causes and treatments for ARFID.

Body Weight Variations

Moreover, because people of all body weights develop ARFID, researchers have considered weight to be an influencing factor for how it progresses.⁶

Differences in brain activation have been reported across the weight spectrum of individuals diagnosed with ARFID. For example, one study showed that "overweight/obese" children diagnosed with ARFID have increased brain activation (as compared to “healthy weight” children diagnosed with ARFID) after viewing high-calorie food pictures.⁶

Here, increased brain activity occurred in regions involved with attentional processing, reward, emotion regulation, and body signals, particularly the orbitofrontal cortex (OFC; a region involved in emotion, reward, and decision-making).⁶

Additionally, children with increased OFC activity prior to a meal reported feeling less satiated following the meal.

Nonetheless, while these findings could help explain variations in ARFID development because participants had additional diagnoses (i.e., autism) and pharmaceutical use (i.e., antidepressants) conclusions should be cautionary.

Sex Differences

Another characteristic of ARFID is that it predominately occurs in males.¹¹

ARFID occurs more often in males than in females, but reasons for this are unknown.

Source: cottonbro/Pexels

We aren't sure why this is, though, as only one study has looked at neurological sex differences associated with ARFID. Here, researchers found no sex differences for brain activation patterns in the OFC and the hypothalamus (an area regulating hunger) after viewing high-calorie food images.⁷ Moreover, men and women showed no significant differences in hormones ghrelin (hunger) and peptide YY (satiety).

Additional research is needed.

The Importance of Context: Case Study 1

Beyond neuroscience, individual case studies can help explain how personal experiences influence illness development. This is vital for a heterogenous disorder like ARFID.

Consider the case of a 27-year-old woman co-diagnosed with ARFID, Gitelman Syndrome (a rare genetic disorder impairing kidney salt absorption), psychosis, and anxiety.⁸

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Throughout her treatment, her psychosis and food restriction persisted, despite fMRI and CT brain scans showing no neurological abnormalities, and her nutrition and electrolyte imbalances being restored.

Consequently, doctors reflected on her personal experiences for clarification. In childhood, the woman showed minor food restriction and anxiety, which were minimized by her participation in and self-identification with athletics.

It was only after injuries sidelined her athletic participation that her symptoms escalated and her psychosis developed. This suggests that, while ARFID does have underlying biological susceptibilities, psychological/social components contribute to its development, as well.

The Importance of Context: Case Study 2

A second case involves a 4-year-old girl, “Sophie." As a child, Sophie learned to associate hunger signals and eating with threats (i.e., stomach pain), likely due to an undiagnosed cow’s milk allergy.⁹ She also had elevated emotionality, which increased her pain sensitivity.

Based on her history, doctors reasoned that her low appetite and poor arousal recognition developed as a way to manage her stomach pain.

While Sophie participated in no neurological studies, her treatment provides insight into what brain regions might influence ARFID development, notably the insula. The insula regulates our internal experiences by telling us when we’re hungry, satiated, and in pain.

Doctors' prescribed treatment for Sophie, the Feeling and Body Investigators (FBI) ARFID Intervention, targets the insula. This intervention has children develop body sensation awareness through interactive experiences with cartoons, and it benefitted Sophie.

Future Directions

Due to its research infancy, we know little about ARFID. Thankfully, an extensive study looking at the neurobiology of ARFID from Dr. Jennifer Thomas at Harvard has been underway for the past few years.⁵ Until we receive more findings from Thomas, let's consider some unanswered questions.

Sensory processing alterations might result in "unusual" feeding patterns.

Source: KoolShooters/Pexels

Difficulties with sensory processing is a core, but under-explored, ARFID feature.¹³ For example, some individuals diagnosed with ARFID might have food color preferences. Understanding these preferences could help explain ARFID onset.

Additionally, we need to investigate interactions between gastrointestinal discomforts, sensory processing, and brain regulation. While we know that these functions influence one another, we don't know exactly how.

Moreover, many individuals are co-diagnosed with autism and ARFID.¹⁵ Better understandings of these relationships could further treatment efficacy.

Finally, neuroscience could inform new ARFID treatments. For example, eye movement desensitization and reprocessing therapy, which uses eye-tracking to "retrain" brain engagement with traumatic memories, has shown to help individuals with ARFID reduce memories of choking.¹⁶