Associations between autism spectrum disorder and eating disorders with and without self-induced vomiting: an empirical study

BACKGROUND Although approximately 23% of anorexia nervosa (AN) patients have concomitant autism spectrum disorder (ASD), it is clinically difficult to determine ASD coexistence in patients with eating disorders. Restrictive AN is more common in younger patients and self-induced vomiting usually appears during adolescence/young adulthood, in order to prevent gaining weight caused by overeating. However, some patients are tolerant of weight gain even if they start overeating. It is important to understand the essential difference between those who vomit and those who do not vomit. In this study, we hypothesised that the absence of self-induced vomiting may be associated with the presence of ASD and aimed to assess the presence of ASD traits in each eating disorder (EDs). Clarifying this association helps to consider the coexistence of ASD in the clinical setting and can lead to the next detailed ASD evaluation, and as a result, helps to determine the appropriate treatment and support individually. METHODS We retrospectively evaluated 43 females aged 15-45 years who attended Chiba University Hospital between 2012 and 2016 using the Eating Disorder Examination Questionnaire (EDE-Q) and Autism-Spectrum Quotient (AQ) to quantify the severity of the EDs and to identify whether ASD traits were present. RESULTS There was no difference in the AQ score between bingeing-purging type AN and restricting type AN. However, there was significant difference in the AQ score between bulimia nervosa and binge EDs (BED). Of the 4 ED subtypes, BED had the highest ASD traits. The non-vomiting group with illness duration < 4 years had a significantly higher AQ communication score than the vomiting group with illness duration ≥4 years. CONCLUSIONS There was a difference in the AQ score by the presence or absence of self-induced vomiting. The results of this study suggest an association between high scores on AQ and non-vomiting. Thus, evaluation of patients for the absence of self-induced vomiting while assessing them for EDs may help us to understand the association with ASD traits.