Scientists studying girls with the eating disorder anorexia have found they show a mild echo of the characteristics of autism - a finding which could point to new ways of helping anorexics overcome their illness.
A study by the leading autism expert Simon Baron-Cohen at Cambridge University's Autism Research Centre found that compared to typical girls, those with anorexia have an above-average number of autistic traits.
They were also found to have an above-average interest in systems and order, and below-average scores in empathy - a profile similar, but less pronounced, to that seen in people with autism, suggesting the two disorders may have common underlying features, Baron-Cohen said.
"Traditionally, anorexia has been viewed purely as an eating disorder. This is quite reasonable, since the girls' dangerously low weight and their risk of malnutrition or even death has to be the highest priority," he said.
"But this new research is suggesting that underlying the surface behavior, the mind of a person with anorexia may share a lot with the mind of a person with autism. In both conditions, there is a strong interest in systems. In girls with anorexia, they have latched onto a system that concerns body weight, shape, and food intake."
People with autism have varying levels of impairment across three main areas - social interaction and empathy or understanding, repetitive behavior and interests, and language and communication.
Cohen noted that autism and anorexia share certain features, such as rigid attitudes and behaviors, a tendency to be very self-focused, and a fascination with detail. Both disorders also share similar differences in the structure and function of brain regions involved in social perception.
As many as one in 50 school age children in the United States are diagnosed with autism. In Europe experts say the rate is around one in 100 children. Most cases are diagnosed in boys.
But Bonnie Auyeung, who worked with Baron-Cohen on this latest research, said its findings suggested a proportion of females with autism may be being overlooked or misdiagnosed because doctors see them first with anorexia.
The study, published in the BioMed Central journal Molecular Autism, tested how 66 girls aged 12 to 18 with anorexia but without autism scored on tests to measure autistic traits.
The researchers compared them to more than 1,600 typical teenagers in the same age range, measuring their autistic traits using a score called the Autism Spectrum Quotient (AQ), their "systemising" using the Systemising Quotient (SQ), and their empathy using the Empathy Quotient (EQ).
They found that compared to typical girls on the AQ, five times more girls with anorexia scored in the range where people with autism score. On tests of empathy and systemising, girls with anorexia had a higher SQ, and a reduced EQ, a profile the researchers said parallels that seen in autism.
Tony Jaffa, who co-led the study, said acknowledging that some anorexic patients may also have a higher than normal number of autistic traits and a love of systems offers specialists new ideas for ways to treat people with the eating disorder.
"Shifting their interest away from body weight and dieting on to a different but equally systematic topic may be helpful," he said. "(And) recognizing that some patients with anorexia may also need help with social skills and communication, and with adapting to change, also gives us a new treatment angle."
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