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Study Supports View that Asperger Syndrome Is Distinct Form of Autism

Brain-activity monitoring shows differences as well as similarities between Asperger syndrome and larger autism spectrum
August 06, 2013

New research documents differences as well as similarities in the brain activity of children with Asperger syndrome and those with other types of autism. The study appears this week in the open-access journal BMC Medicine.

The findings may have implications on how best to help those with Asperger syndrome as compared to others on the autism spectrum, the researchers suggest. They also raise concerns with the recent decision to fold different subtypes of autism – including Asperger syndrome – into one unified diagnosis of autism spectrum disorder (ASD).

"This study offers new evidence suggesting that biological differences may be used alongside behavioral observations to define subsets of individuals living on the autism spectrum," comments Autism Speaks Chief Science Officer Robert Ring. "However, it’s important to point out the preliminary nature of these findings. It’s too early in this specific research story to draw concrete conclusions." 

Differences and similarities
The researchers – at Harvard Medical School and Boston Children’s Hospital – used electroencephalography (EEG) to track brain signaling in more than 400 children with autism. Twenty-six of these children had a diagnosis of Asperger syndrome. For comparison, the researchers looked at the EEGs of 550 typically developing children.

All the children with autism – including those with Asperger syndrome – showed weaker connections in a language-associated region of the brain’s left hemisphere. However, the researchers found distinctively strong activity in other areas of the brain among the children with Asperger syndrome. This distinctive activity was not seen in either the other children with autism or the typically developing children. As the number of children studied was relatively small, the researchers call for further research to confirm their findings.

Implications for ASD diagnosis
Like others with autism, individuals who have Asperger syndrome tend to have difficulties with social interaction and repetitive behaviors or restricted interests. However, unlike others on the autism spectrum, those diagnosed with Asperger syndrome tend to show typical or even advanced language development.

Prior to this year, psychiatrists and psychologists recognized several distinct subtypes of ASD. These included Asperger syndrome, autistic disorder and pervasive developmental disorder-not otherwise specified (PDD-NOS). In May, the American Psychiatric Association adopted new diagnostic guidelines that folded the previously separate subtypes into one diagnosis of ASD. (For more information, see our complete DSM-5 coverage.)

"It’s premature to allow a study like this to influence the larger debate around how Asperger’s diagnoses have been handled in the new DSM-5," Dr. Ring cautions. Autism Speaks is proactively monitoring the effects of the DSM-5 on autism diagnosis and related services. As part of this effort, Autism Speaks invites individuals, parents and providers to provide feedback through an online survey of experiences with the DSM-5. (Follow the link to access the survey.)


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