A Genetic Link Between Anorexia and Autism?

At the Eating Disorders Unit at the Maudsley Hospital in London, anorexia is not seen as a social disorder — or even primarily a psychological one. While most American treatment providers blame perfection-seeking parents and the media's idealization of hollow-cheeked actresses for eating disorders (among other dysfunctional behaviors), researchers at Maudsley believe the root cause has little to do with social pressure. Rather, they think anorexia is better explained by heredity — perhaps by some of the same genes associated with autism.

The London researchers have been studying the commonalities between these two conditions for several years. On the surface, they appear entirely different — in autism, patients have difficulty connecting with people in the outside world, while in anorexia, sufferers seem consumed by other people's perceptions — but Maudsley researchers point out that the salient characteristics of each illness are similar. (See six tips for traveling with an autistic child.)

For example, both anorexic and autistic patients have a tendency to behave obsessively and suffer from rigid ways of thinking. Tic disorders, which commonly affect people with autism, are found in 27% of people with severe anorexia. And in both conditions, patients have difficulty with "set-shifting," or changing course mentally.

"Both autism-spectrum conditions and anorexia share a narrow focus of attention, a resistance to change and excellent attention to detail," says Simon Baron-Cohen, director of the Autism Research Centre at Cambridge University, who is not involved in the Maudsley research.

In addition, says Janet Treasure, director of the Maudsley Eating Disorders Unit, past research suggests that about 15% to 20% of patients with anorexia may also have Asperger's syndrome, an autism-spectrum disorder. Research also shows that the conditions occur together in families more often than they would by chance. It's possible, she says, that the same genetic predisposition for autism and anorexia may be expressed differently depending on gender. (Read "A Link Between Autism and Testosterone?")

About 15 times as many boys are given a diagnosis of Asperger's syndrome as are girls, and nearly 10 times as many girls develop anorexia as boys. It's easy to see how an outsized sense of perfectionism in a female might lead to an unhealthy obsession with thinness — given society's preoccupation with physical appearance — while a male might end up obsessing about cars or trains, which is typical in autistic boys. "The reason [Asperger's] is usually diagnosed less often in females may be because it takes a different form — anorexia may be just one of the forms," says Baron-Cohen, adding that there are likely multiple routes leading to anorexia and that autistic features may not factor in all of them.

Treasure has found that starvation itself intensifies autistic characteristics like rigidity and obsession — a phenomenon that applies to all people, but particularly those with anorexia. "When they are underweight, people with anorexia get even more like people with autism," says Treasure. "They can't interpret other people's emotions, they can't regulate their own emotions, and they get overwhelmed when they are frightened or angry."

In fact, in a study published this month in the journal Clinical Psychology and Psychotherapy, Treasure and colleagues found that underweight anorexics performed poorly on a classic test of understanding others' emotions that was devised by Baron-Cohen to study such defects in people with autism-spectrum disorders. The theory is that hunger focuses the brain so sharply on the task of getting food that, as with other stressors, it shuts down higher cognitive functions, like reading other people's emotions.

And according to Dr. Eric Hollander, an attending psychiatrist at Montefiore Medical Center in New York City and an expert on autism, there is evidence that the "repetitive thoughts and behaviors, rigid routines and rituals and perfectionism" that characterize both autism and anorexia may be traced to the same regions in the brain. Imaging studies of patients with either condition have found variations in the activity of brain regions like the anterior cingulate cortex, for example, where disruptions contribute to obsessive-compulsive behavior and aberrant social behaviors.

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