The average age at which children are diagnosed with autism is between three and four, but scientists have long suspected that the disorder starts much earlier. A key piece of evidence is a phenomenon known as brain overgrowth. Autistic toddlers tend to have large brains for their age, and researchers have shown a correlation between the degree of excess growth and the severity of autism symptoms. Eric Courchesne, director of the Autism Center of Excellence at the University of California, San Diego, helped to pioneer the overgrowth hypothesis. Now he and his colleague Cynthia Schumann have published data that suggest the excess brain growth starts in the first year of life, if not sooner.
The study, published in a recent issue of the Journal of Neuroscience, is the first to evaluate brain growth and autism throughout early development. Using cross-sectional MRI scans, the U.C.S.D. researchers found overgrowth in autistic subjects as young as one and a half. At two and a half, the autistic subjects’ brains were 7 percent larger on average than the control group’s. Although why, exactly, excessive brain growth is related to autism remains a mystery, the new work helps to confirm that signs of the disorder appear early—knowledge that could lead to detection and treatments, such as behavior therapy, at a younger age. “The earlier the intervention, the better the outcome,” Courchesne says.
This article was originally published with the title Too Much, Too Young.
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Add CommentChildren with autism are statistically more likely to have had complications at birth and to have been firstborn children. Could the use of diagnostic x-rays during labor contribute to brain overgrowth in these infants? The use of x-rays to determine cephalopelvic dysproportion would decrease in subsequent births to the same mother, as they would likely be given scheduled cesarean births rather than emergency c-sections.
Reply | Report Abuse | Link to this.lot of
Reply | Report Abuse | Link to thisI disagree with this theory. I had no complications with the birth of my daughter. It was the easiest of five births. The two that were difficult do not have autism. In our case, it runs in the family, with her father, cousin and grandfather also being somewhere on the spectrum.
Reply | Report Abuse | Link to thisI have several friends with children with varying degrees of autism (mostly Aspergers). In my discussions with the parents, there has always been someone in the previous generation who also showed signs of being on the autistic spectrum. I am not saying this is always the case. But there appears to be a familial link in the vast majority of my acquaintances.
One of the most characteristic feature of autism is increased number of minicolums (a feature of brain anatomy). The number of minicolums is fixed in the first trimester in utero.
Reply | Report Abuse | Link to thisNothing later in life can increase that number. X-rays would decrease it, neurotoxins would dcrease it, trauma at birth would decrease it.