Sex-specific mechanisms for eating disorder risk in men and women with autistic traits: the role of alexithymia.

ABSTRACT

BACKGROUND: A poorly understood relationship exists between eating disorders (ED) and autism spectrum conditions (ASC henceforth 'autism'). ED are more prevalent in autistic people and people with high autistic traits, and autistic features are prognostic of longer illness. Aiming to understand what increases the risk of ED in relation to autism and autistic traits, previous research has implicated alexithymia as a causal mechanism in this relationship. These studies could not, however, disentangle whether alexithymia explains the relationship between ED pathology and autistic traits directly or through its impact on anxious/depressive symptoms, which in turn result in higher ED symptomatology. Moreover, despite evidence for sex differences in the aetiology of ED, little research has examined the impact of sex on these relationships. METHODS: Focusing on the association between autistic traits and ED psychopathology, we examined independent mediating effects of alexithymia and anxious/depressive symptoms, as well as sequential mediation effects where alexithymia affects ED psychopathology via its impact on anxious/depressive symptoms. Participants were 198 men and 265 women with formally diagnosed and suspected ED, who completed an online survey of standardised scales. RESULTS: In men, higher autistic traits were associated with ED psychopathology sequentially via greater alexithymia and through that, greater depressive/anxious symptoms. In women, alexithymia mediated the relationship between autistic traits and ED psychopathology both directly and sequentially through its impact on anxious/depressive symptoms. Interestingly, depressive/anxious symptoms also mediated that relationship independently from alexithymia. CONCLUSIONS: While cross-sectional, these findings suggest that the relationship between autistic traits and ED symptomatology is mediated by other variables. In support of its proposed role in the aetiology of ED, alexithymia was directly associated with ED symptoms in women. It also affected ED symptoms indirectly, in all participants, via its effect on depressive/anxious symptoms. Interventions focusing on alexithymia may facilitate recovery not only via their effect on ED, but via their effect on other forms of state psychopathology which contribute to the maintenance and development of ED. Sex differences, however, reflect that alternative therapeutic targets for men and women may be beneficial.

Autistic individuals seem to be at higher risk of developing eating disorders (ED)­even just having autistic traits seems to elevate risk of ED, although we do not understand why. One possibility is that autism and autistic traits are closely related to alexithymia, a difficulty identifying and describing your emotions, and it may be this that increases risk of ED. To test this, we explored relationships between autistic traits and ED symptoms in men and women with ED, who completed an online survey. In men, we found that autistic traits were associated with ED symptoms because they were associated with alexithymia, and alexithymia was associated with ED symptoms because it was associated with anxious/depressive symptoms. The same was true in women, but anxious/depressive symptoms were also associated with ED symptoms in their own right. While these findings need to be investigated in more thorough longitudinal approaches, they suggest that pathways to ED differ slightly between men and women, autistic and non-autistic, and that therapeutic interventions should also differ. In both sexes, the fact that alexithymia was associated with ED symptoms and those of other mental illnesses that seemed to contribute to ED, suggests that it should be targeted in interventions.