Brain changes responsible for language deficits in autism.
New MR brain imaging research shows clear brain differences between autistic boys with language impairment and those with normal language development. The study also found a link between autistic patients and those with a rare language impairment who are otherwise functionally normal.
Language deficits are among the core impairments of autism. In most right-handed people without autism, the left hemisphere of the brain dominates the understanding and production of language. Language centers such as Broca's area, which is named for the 19th century French neurologist Paul Broca, are correspondingly larger on the left side of the brain in most right-handed people. Previous research has shown that the situation is reversed in some right-handed boys with autism. In those boys, Broca's area was larger on the right side, on average, than the left.
Researchers looked at MR results from 22 right-handed autistic boys and 9 boys with a rare disorder called Specific Language Impairment, or SLI. Children with SLI have delayed language development, but their cognitive and social-emotional development proceeds normally. The boys with autism were divided into those with language impairment and those with normal language ability. Researchers also looked at results from 11 control subjects.
MR results showed that Broca's area is apparently normal in autistic boys who have normal language capabilities. However, autistic boys with language problems have brain changes that match those seen in boys with SLI.
"This study is the first to show a direct, brain-based link between autism, SLI and language ability," said Gordon J. Harris, Ph.D., of Massachusetts General Hospital in Boston. "Both groups of boys with language impairment--both the autism and SLI groups--showed the reversal of language area asymmetry, while both groups of language-normal boys, both the autism and control language normal groups, had typical asymmetry." The study appeared in the Oct. 11 online edition of the Annals of Neurology.
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|Title Annotation:||Research & Technology|
|Date:||Nov 1, 2004|
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