PURPOSE: Previous studies have shown links between autism spectrum disorder and anorexia nervosa restricting type. However, few have examined the association between autism spectrum disorder and other eating disorder subtypes, such as bulimia nervosa, anorexia nervosa binge-purging type and binge eating disorder. In this study, we aimed to assess the presence of autism spectrum disorder tendencies in each eating disorder and to explore whether an association exists between traits of autism spectrum disorder and eating disorders with or without self-induced vomiting.
METHODS: We retrospectively sampled outpatients who attended Chiba University Hospital between 2012 and 2016 (43 females aged 15–45 years). All were assessed using the Eating Disorder Examination Questionnaire and Autism Spectrum Quotient to quantify the severity of the eating disorder and to identify whether autism spectrum disorder traits were present. Additionally, the subtype at onset, the change in subtype from onset to presentation and the difference based on the presence or absence of self-induced vomiting were investigated.
RESULTS: We found that the Autism Spectrum Quotient tended to be higher in the group without, than in the group with, self-induced vomiting. Patients with binge eating disorder had the highest Autism Spectrum Quotient at presentation, and most of them had transitioned from prior anorexia nervosa restricting type.
CONCLUSION: Of note, although their subtype had changed over time, the trait of not vomiting had remained consistent. There was a difference in the Autism Spectrum Quotient score by the presence or absence of self-induced vomiting.
Level of Evidence: LEVEL IV (Evidence obtained from multiple time series without the intervention).
Plain English Summary
It is known that 18%–23% of patients with anorexia nervosa have comorbid autism spectrum disorder. However, no study has examined the association with autism spectrum disorder by subtypes of anorexia nervosa (restring type and binge with self-induced vomiting type). In addition, no studies have examined the association of autism spectrum disorder with other subtypes of eating disorders.
As a result of examining the autism spectrum disorder tendency for each eating disorders subtype, it was found that the type of eating disorders that did not self-induced vomiting had a higher autism spectrum disorder tendency than with self-induced vomiting.
Overall, 80% of people diagnosed with binge eating disorder had been diagnosed with restricting type of anorexia nervosa at the time of onset. For some restricting type of anorexia nervosa patients, fear or aversion to vomiting can be stronger than the desire not to gain weight, it may be the influence of the autism spectrum disorder tendency.