Since Gillberg's (1985) and others initial suggestion of relationship between anorexia nervosa and autism, a large scale longitudinal study into teenage onset anorexia nervosa conducted in Sweden confirmed that 23% of people with a long-standing eating disorder are on the autism spectrum. Those on autism spectrum tend to have a worse outcome, but may benefit from the combined use of behavioural and pharmacological therapies tailored to ameliorate autism rather than anorexia nervosa per se. Other studies, most notably research conducted at the Maudsley Hospital UK, furthermore suggest that autistic traits are common in people with anorexia nervosa, shared traits include e.g. executive function, autism quotient score, central coherence, theory of mind, cognitive-behavioural flexibility, emotion regulation and understanding facial expressions.
Zucker et al. (2007) proposed that conditions on the autism spectrum make up the cognitive endophenotype underlying anorexia nervosa and appealed for increased interdisciplinary collaboration (see figure to right). A pilot study into the effectiveness Cognitive Behaviour Therapy, which based its treatment protocol on the hypothesised relationship between anorexia nervosa and an underlying autistic like condition, reduced perfectionism and rigidity in 17 out of 19 participants.