Autism: New Evidence that Brain Changes Begin in Pregnancy

MedicalResearch.com Interview with:
Dr. Erik Courchesne PhD
Professor, Department of Neurosciences
UC San Diego School of Medicine

MedicalResearch.com: What are the main findings of the study?

Dr. Courchesne: “Building a baby’s brain during pregnancy involves creating a cortex that contains six layers,” Courchesne said. “We discovered focal patches of disrupted development of these cortical layers in the majority of children with autism.” The authors created the first three-dimensional model visualizing brain locations where patches of cortex had failed to develop the normal cell-layering pattern.

The study found that in the brains of children with autism key genetic markers were absent in brain cells in multiple layers. “This defect,” Courchesne said, “indicates that the crucial early developmental step of creating six distinct layers with specific types of brain cells – something that begins in prenatal life – had been disrupted.”  The study gives clear and direct new evidence that autism begins during pregnancy.

MedicalResearch.com: Were any of the findings unexpected?

Dr. Courchesne: Equally important, is that these early developmental defects were present in focal patches of cortex, suggesting the defect is not uniform throughout the cortex. The brain regions most affected by focal patches of absent gene markers were the frontal and the temporal cortex, possibly illuminating why different functional systems are impacted across individuals with the disorder.

MedicalResearch.com: What should clinicians and patients take away from your report?

Dr. Courchesne: The frontal cortex is associated with higher-order brain function, such as complex communication and comprehension of social cues. The temporal cortex is associated with language. The disruptions of frontal and temporal cortical layers seen in the study may underlie symptoms most often displayed in autistic spectrum disorders. The visual cortex – an area of the brain associated with perception that tends to be spared in autism – displayed no abnormalities.

“The finding that these defects occur in patches rather than across the entirety of cortex gives hope as well as insight about the nature of autism,” added Courchesne.

Such patchy defects, as opposed to uniform cortical pathology, may help explain why many toddlers with autism show clinical improvement with early treatment and over time. The findings support the idea that in children with autism the brain can sometimes rewire connections to circumvent early focal defects, raising hope that understanding these patches may eventually open new avenues to explore how that improvement occurs.

MedicalResearch.com:  What recommendations do you have for future research as a result of this study?

Dr. Courchesne:  Future research will focus on finding out what intrauterine and genetic events cause these focal patches of disorganized cortex. Knowing the cause may one day lead to steps to prevent these abnormal patches from developing, or to improve ways to rewire the brain to circumvent these patchy defects so the child has a better outcome. Developing brain imaging methods to detect where the patches are in each child might also lead to developing individualized prognostic and treatment approaches.

Citation:

Patches of Disorganization in the Neocortex of Children with Autism

 Stoner R, et al “Patches of disorganization in the neocortex of children with autism” N Engl J Med 2014; 370: 1209-1219.

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