Alexithymia: the missing link between autism and eating disorders?
Autism is diagnosed in 37% of those with eating disorders as compared to 1% in the general population, and such co-occurrence is associated with poorer treatment outcomes (Westwood et al, 2016). While research has examined potential shared genetic vulnerabilities, a thus-far neglected possibility is that alexithymia – the inability to identify and describe emotions links the two conditions and increases the risk of their comorbidity, since it is often present in both. We tested this hypothesis in a group of healthy 374 university students (n=53 males; mean age = 22.0) using standard questionnaires to measure alexithymia (TAS, Bagby, Parker, & Taylor, 1994), autistic traits (AQ, Baron-Cohen, Wheelwright, Skinner, Martin, & Clubley, 2001) and eating disordered behaviours (EAT-26, Garner & Garfinkel, 1979). We found that autistic traits significantly predicted eating disorder symptoms, b= .21, t(372)=4.16 p<.001. We also found that alexithymia significantly predicted both eating disorder symptoms and autistic traits, b=.33, t(371)=5.86, p<.0001, and b=.50, t(372)=11.1, p<.0001 respectively. Most interestingly, we found that the relationship between the AQ and the EAT was no longer significant after controlling for alexithymia, b=.05, t(371)=.84, p=.403, suggesting that alexithymia fully mediates this relationship. While our results need to be replicated in clinical populations, they could have implications for the diagnosis of autism in individuals with eating disorders and ultimately improve treatment outcome in individuals suffering from both disorders concurrently.