Key Brain 'Networks' May Differ in Autism
Neural systems tied to gauging social cues appear 'over-connected' in children with the disorder
By Kathleen Doheny
WEDNESDAY, April 16, 2014 (HealthDay News) -- Differences in brain connectivity may help explain the social impairments common in those who have autism spectrum disorders, new research suggests.
The small study compared the brains of 25 teens with an autism spectrum disorder to those of 25 typically developing teens, all aged 11 to 18. The researchers found key differences between the two groups in brain "networks" that help people to figure out what others are thinking, and to understand others' actions and emotions.
"It is generally agreed that the way the networks are organized is not typical [in those with autism]," explained study lead researcher Inna Fishman, assistant research professor of psychology at San Diego State University.
The prevailing idea until now, she said, has been that these neurological networks are under-connected in people with autism. However, "we found they were over-connected -- they talk to each other way more than expected at that age."
The study is published in the April 16 online edition of JAMA Psychiatry.
According to recent statistics issued by the U.S. Centers for Disease Control and Prevention, about one in 68 children in the United States has been identified with an autism spectrum disorder. Boys are about five times more likely to be affected than are girls.
Fishman said the approach her team took in the study is a relatively new one.
"In the last seven to 10 years, people began to understand that we shouldn't be searching for answers in any individual brain area, but looking at the brain as a collection of networks," she said.
In the study, Fishman's team used functional MRI scans to look at the connectivity in two brain networks, both involved in social processing. One is the "mentalizing" system, also known as the theory of mind. It helps a person infer what others are thinking, their beliefs and intentions. The other is the "mirror neuron" system, which helps people understand the meaning and actions of another by replicating them.
People with autism show differences in this connectivity compared to typically developing people, and it predominately manifests as over-activity, Fishman's team noted. The researchers also found that the greater the differences in neural connectivity, the more severe the child's social skill problems.