Out-of-Sync Brain May Be a Clue to Autism

Study Shows Toddlers With Autism Have Abnormal Synchronization in Brain's Communication Area

Medically Reviewed by Laura J. Martin, MD on June 22, 2011
From the WebMD Archives

June 22, 2011 -- A brain that is out of sync may be an early clue of autism, researchers suggest.

Toddlers with autism are more likely to have abnormal synchronization between certain brain areas than other kids the same age, even those with language delays, according to a new study.

''There seems to be impaired or reduced synchronization between the right and left hemispheres, specifically the areas involved in language and communication," says researcher Ilan Dinstein, PhD, a postdoctoral fellow at the Weizmann Institute of Science in Rehovot, Israel.

The study was done at the University of California, San Diego. It is published in the journal Neuron.

The researchers found only a link between the abnormality and autism, not cause and effect, Dinstein says. Still, the discovery may someday help experts develop tools to diagnose the condition earlier, he says.

Autism and autism spectrum disorder are a range of neurodevelopmental disorders marked by difficulties in social and communication skills and repetitive behavior. About one in 110 U.S. children are affected, according to CDC estimates.

Coordination of Brain's Tasks

Synchronization helps coordinate the brain's different tasks, Dinstein says. "Your brain is set up to do specific tasks." Some involve vision, for instance, or motor skills or decision making.

"While all these different parts are doing different things, they have to be coordinated," he says. For normal brain development, this coordination seems to be very important, he tells WebMD.

Other recent research on adults and teens with autism has found problems in this coordination, too, Dinstein says. That led them to look at younger subjects.

The researchers used functional MRIs (fMRIs) to evaluate 72 toddlers, ages 1 to 3.5, during sleep. Of the 72 participants, 29 had autism, 30 were typically developing, and 13 had language delays. The fMRIs were done while the children were in similar stages of sleep.

Compared to both other groups, those who had a diagnosis of autism had weaker correlations between hemispheres in two areas commonly linked with language production and comprehension. These areas are the inferior frontal gyrus and superior temporal gyrus.

The abnormal synchronization was evident in 70% of those with autism. However, just a handful of the other children had it.

The researchers also found that the weaker the synchronization, the more severe the communication problems for the autistic children.

This suggests that the poor synchronization is found at the earliest stages of the disorder and could be linked to the severity, the researchers say.

If the findings bear out, earlier diagnosis may be possible, Dinstein says. That would make earlier intervention possible, of course.

It's possible that the reduced synchronization is a by-product of something else causing the autism, he says. ''The fact that this phenomenon is evident in 70% of kids [with autism] does not mean it is the biology causing the autism," he says. "There could be a different biological mechanism causing both the autism and the reduced synchronization."

However, even if the the abnormality is a by-product of something else causing the condition, he says, that would still be useful information for making a diagnosis.

Typically, a child is age 3 or older before a diagnosis of autism is made, he says.

Connection Failure in the Brain

The study reinforces some research and breaks some new ground, according to Geraldine Dawson, PhD, chief science officer for Autism Speaks. She reviewed the report but did not participate in the research.

"Some have described autism as a 'developmental disconnection syndrome' because several studies have found that there is a failure of long-range connectivity between different brain regions in autism," she says. "This helps explain why people with autism have trouble with complex behaviors, such as social interaction and language, which require coordinated activity across several brain regions."

It is the first study, she believes, ''to show reduced functional connectivity in very young children with autism." The study, she says, suggests this abnormality is an early characteristic of the disorder. It helps explain some symptoms seen early on, she says. "Even early gestures and social games require coordinated activity among several brain regions."

Show Sources


Ilan Dinstein, PhD, postdoctoral fellow, Weizmann Institute of Science, Rehovot, Israel.

Geraldine Dawson, PhD, chief science officer, Autism Speaks.

Dinstein, I. Neuron, June 23, 2011; vol 70: pp 1218-1225.

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