Part 3 – The link between ASD and Eating Disorders

By: Amber Whittemore RD BSN MHSc

**Disclaimer: this blog gives general evidence-based links between some common associations between ASD and eating disorders (ED’s), these may or may not apply to your child or adolescent. As a parent, you know your child best and adapting strategies that work best for you and your family is key**

Welcome back to the HEC blog, where today we will be focusing on the links between autism spectrum disorder (ASD) and disordered eating patterns.

We know from the previous few blogs, and or your personal experience, having a child or adolescent with ASD can pose some complications with normalized eating patterns and behaviours. These can be influenced by a variety of factors as outlined in the previous posts. When focussing more specifically on disordered eating patterns, tendencies such as rigidity in thinking, lack of flexibility with food and patterns, challenges with executive functioning, and/or perfectionistic tendencies tend to play a large role1.

How common is it that ASD and ED’s overlap?

A 2013 review2 of all available and relevant literature on the subject found that there were significantly raised rates of ASD in eating disorder (ED) populations when compared to neurotypical control populations. The rates of ED’s in the ASD population were found to be 22.9%2, with another community sample finding that the prevalence was 24%, significant compared to the 2% prevalence in the neurotypical control groups3. Of note, this research was done with adults and not with children or adolescents.

Much of the research investigating these links focuses specifically on Anorexia Nervosa (AN) in women with ASD, who are significantly overrepresented among individuals in treatment4. With this said, we know that males are significantly underrepresented in ED treatment settings due to stigmatization around the topic, and therefore it is not unrealistic to expect that males with autism have similar experiences. It has been consistently found that 20-35% of women with AN meet criteria for ASD5, whereas less than 1% of the general female population meet the criteria for ASD6. 

Why are these two disorders overlapped?

There has been a considerable amount of research investigating the links between ASD and ED’s in recent years, and from this, there have been three distinct features that commonly overlap these disorders. They are:

  1. Impaired “theory of the mind”2: this is referring to the impaired ability to view situations or mindsets from another individual’s perspective, and instead only being able to view them from one’s own perspective.
  1. Impaired “central coherence”2: this is referring to the inability or difficulty with seeing the “bigger picture” of situations, and rather focussing on the individual details.
  1. Impaired “set-shifting”2: this is referring to difficulty with shifting between activities or actions, and rather experiencing discomfort or the inability to shift between said actions effectively.
  1. Difficulty processing emotions4, or Alexithymia2: this refers to the inability to identify and describe mental states or emotions, is also a common link between ASD and Anorexia Nervosa (AN) specifically.
  1. Cognitive rigidity4: this is referring to difficulty with thinking about situations or patterns in a different way than is current or usual.

These overlapping mindsets prompted the theory that disordered eating and ASD are related conditions based on the similarities in their cognitive profiles

What are the signs and triggers of a concurrent ED and ASD?

In 2019 an interview7 was conducted with a group of women who met the criterion for AN and ASD. This interview was able to find several patterns in the development and perpetuation of these women’s ED’s – which may serve as clues to keep an eye out for. The women also reported that the most common reported motivators for the development of an ED, such as weight loss or low self-esteem, were less relevant for them and instead the triggers and motivators were as follows:

  • Rigidity and inflexibility contributing to fixed routines and rituals around food
  • Need for control with food
  • Sensory difficulties with food
  • Social difficulties or confusion
  • Environmental problems surrounding cooking and grocery shopping
  • Exercise as a method of stimulation
  • ED acting as a special interest

In 2020 another interview4 was held with a group of women who struggled with ASD and AN, their parents and health care professionals treating said women. This interview generated similar themes relating to the development and maintenance of these women’s ED’s, as well as common moderating factors that played into the onset of them. The most common factors outlined in the pathway to an ED in these women were bullying, unrecognized autism, stressful life events, and puberty.

Being able to recognize these themes and factors in your child or adolescent may serve to identify disordered patterns earlier, making it possible to seek help earlier to cultivate healthier patterns. The themes from the 2020 interview4 were as follows:

Sensory sensitivities and or overload with food specifically (texture, taste, smell, temperature, mixing items) can lead to a limited range of foods, perpetuating fear around certain foods or meals. Discomfort or confusion with sensory overload, which could be related to noise, touch, certain lighting, etc., may lead to starvation as a mode to numbing these sensations. There are several crossovers between food-specific sensitivities, restriction of said foods/food groups, and the presentation of Avoidance/Restrictive Food Intake Disorder (ARFID), an ED that is not driven by concerns surrounding weight or shape8. 

Internal and bodily sensations that are associated with eating, such as feelings of fullness, bloating, and/or digestion can be distressing for some individuals with ASD. This may lead to food restriction to avoid these internal sensations. In addition, the feeling of putting on weight or the stomach feeling larger can be a trigger for restriction (versus the thought process of not liking how the body or stomach looks). Additionally, difficulties with interpreting and/or understanding eating-related sensations, such as hunger and fullness were found. 

Social interaction and relationships can be difficult for some individuals on the spectrum – this combined with experiences of loneliness, bullying, or abuse can affect an individual’s eating. The women reported that restricting their intake was a way to cope with and/or numb the subsequent emotions that came from social difficulties. Another way in which social difficulties were linked to the onset of these women’s ED’s was through the restriction of social settings that involve food, such as school lunches, due to the social or sensory overload of the environment, and the fear of being isolated or bullied.

Self and identity played into the development of these women’s ED’s as they reported lacking a strong sense of self, feeling different, and not fitting in. These feelings of difference were often harboured as being one’s own fault or a personal failing, which reportedly lead to trying to cope with ED behaviours. For some of the women interviewed their experiences with not fitting in lead them to believe the cause was related to their body or appearance. 

Thinking styles such as literal thinking, obsessive and intense interests, cognitive rigidity, and the need for control can increase the risk of individuals with ASD developing an ED. This is due to a heightened vulnerability with developing food and eating rules/rituals, as well as increased difficulty with shifting focus away from said rules/rituals once they have been established. Literal thinking can lead to distortions in thought processes, or “all or nothing” thinking, surrounding food and the body, which can give rise to ED behaviours. 

Special interests that revolve around food, diet, nutrition, the body, exercise, or even counting numbers, can give rise to unhealthy patterns that may increase the risk of an ED. 

The Bottom Line

We know that ASD and ED’s are common co-morbidities, and through today’s blog, we were able to get a deeper understanding of how and why these two disorders so commonly co-exist.

The research suggests that some of the most common factors that play into the development of ED’s include areas of ASD-related difficulties, such as sensory sensitivities, difficulty with internal or bodily sensations, social interactions, and thinking patterns. Some of the most common moderating factors that play into the actual onset of an ED are bullying, unrecognized autism, stressful life events, and puberty.

Stay tuned for part four of this blog series, where we will focus on ways to intervene and help your child or adolescent if they are struggling with signs of or a diagnosis of disordered eating.

References

1Sara Garner for Northern Health. (2020). 6th Annual Interior Region Eating Disorder Forum: Eating Disorders and Autism Spectrum Disorder: Recognizing and Responding to the Needs of Girls and Women in Eating Disorder Treatment.

2Huke, V., Turk, J., Saeidi, S., Kent, A. & Morgan, J.F. (2013). Autism Spectrum Disorders in Eating Disorder Populations: A Systematic Review. Eur. Eat. Disorders Rev., 21: 345-351. https://doi-org.ezproxy.lib.ryerson.ca/10.1002/erv.2244

3Rastam, M., Gillberg, C., & Wentz, E. (2003). Outcome of teenage onset anorexia nervosa in a Swedish-community based sample. European Child & Adolescent Psychiatry, 12, 78–90.

4Brede, J., Babb, C., Jones, C. et al. “For Me, the Anorexia is Just a Symptom, and the Cause is the Autism”: Investigating Restrictive Eating Disorders in Autistic Women. J Autism Dev Disord 50, 4280–4296 (2020). https://doi-org.ezproxy.lib.ryerson.ca/10.1007/s10803-020-04479-3

5Westwood, H., & Tchanturia, K. (2017). Autism spectrum disorder in anorexia nervosa: An updated literature review. Current Psychiatry Reports, 19(7), 41. https ://doi.org/10.1007/s1192

0-017-0791-9.

6Loomes, R., Hull, L., & Mandy, W. P. L. (2017). What is the male-to female ratio in Autism Spectrum Disorder? A systematic review and meta-analysis. Journal of the American Academy of Child and Adolescent Psychiatry, 56(6), 466–474. https ://doi.org/10.1016/j. jaac.2017.03.013.

7Kinnaird, E., Norton, C., Stewart, C., & Tchanturia, K. (2019). Same behaviours, different reasons: What do patients with co-occurring anorexia and autism want from treatment? International Review of Psychiatry, 31(4), 308–317. https ://doi.org/10.1080/09540 261.2018.15318 31.

8American Psychological Association. (2013). Diagnostic and statistical manual of mental disorders. Arlington, VA.: American Psychiatric Publishing.