WEDNESDAY, Nov. 3 (HealthDay News) -- People with a common genetic variant that's associated with autism have a "disconnect" between their frontal lobe and other areas of the brain important for language, brain scans show.
The disconnect may help explain some of the language and communication difficulties that are characteristic of autism, researchers report in the Nov. 3 issue of Science Translational Medicine.
About one-third of all people carry the variant of the CNTNAP2 gene that is associated with a heightened risk of autism, as well as attention-deficit/hyperactivity disorder, Tourette syndrome, schizophrenia and other language difficulties.
In the study, researchers performed functional MRI brain scans -- which measure blood flow in the brain -- on 32 children who had the gene variant. Half had an autism spectrum disorder, while half were developing normally.
Regardless of whether the kids had autism or not, children with the CNTNAP2 "risk" gene showed more activity in the frontal lobe of the brain (specifically, inside the prefrontal cortex) during a "language learning" task than those without the risk gene.
In those without the risk gene, activity in the prefrontal cortex decreased during the task. Instead, there was more connectivity between the frontal lobe and other areas of the brain, including the left side of the brain, which is involved with language.
In children with the risk gene variant, brain scans showed that the frontal lobe was "over-connected" to itself rather than connected in a normal fashion with the rest of the brain.
"In the kids who carry the risk version, instead of having nice clean connections between frontal lobe and the left side of the brain where you process language, you see more of a broad connection throughout the frontal lobe, almost as if it's talking to itself," said lead study author Ashley Scott-V
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