New study sheds more light on when — and where — autism develops in the brain
David Goldman, Associated Press
A small exploratory study of the brains of children who have autism has shown that some abnormalities appear to form early in fetal development. The differences are seen in certain brain layers.
The research, led by Eric Courchesne and Rich Stoner from the University of California San Diego Autism Center of Excellence, is published in the March 27 New England Journal of Medicine.
They analyzed brain tissue of children ages 2 to 15 who had died, including both those with and those without autism. By examining gene expression in the brain tissue, they were able to locate abnormal neurons in some of the brain layers.
"While autism is generally considered a developmental brain disorder, research has not identified a consistent or causative lesion," Dr. Thomas R. Insel, director of the National Institute of Mental Health, noted in a written statement. "If this new report of disorganized architecture in the brains of some children with autism is replicated, we can presume this reflects a process occurring long before birth. This reinforces the importance of early identification and intervention."
In background information, the researchers explained that during brain development, neurons within the cortex form six layers, each with different types of cells and connection patterns. The researchers looked at cellular markers and found them absent in 91 percent of the samples taken from children who had had autism. That was true of only 9 percent of the other samples.
The difference was found in focal patches encompassing multiple layers of the cortex in both the frontal and temporal lobes, they said. Those are the parts of the brain that control social and emotional communication and language functions.
"Considering that disturbances in these types of behaviors are hallmarks of autism," the NIMH summary said, "the researchers conclude that the specific locations of the patches may underlie the expression and severity of various symptoms in a child with the disorder."
"Each patient's constellation of symptoms may depend strongly on where the patches occur and how many of them there are," Stoner told Reuters Health.
"I'm hoping (the new findings) are going to drive more research in this area so we can figure out what these are and figure out what the cells are like in these regions, and start to integrate this with some of the genetic findings," Stoner added.
Early diagnosis and treatment has been shown to help. The researchers theorize that such improvement may occur because the defect does occur in patches, which means there is normal brain tissue in between. With treatment, the other parts of the developing brain may create new connections that allow the child to "sidestep" some of the challenges associated with autism.
NIMH helped fund the study.
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