Autism is a developmental disability characterised by social interaction difficulties and inability to relate to others. Symptoms vary widely but typically do not emerge until two or three years although signs can be detected earlier than this age.
Emerging research presents new findings that the disorder starts during pregnancy.
Researchers from the Autism Center of Excellence at UC San Diego and the Allen Institute for Brain Science discovered patches of disrupted development in the cortex in postmortem brain tissue from children with autism. The same characteristic patches were not found in samples from tissue taken from children without autism.
The findings give deeper insight on how genes affect brain development and support the need for early therapeutic intervention.
“Building a baby’s brain during pregnancy involves creating a cortex that contains six layers,” said Eric Courchesne, Ph.D., director of the Autism Center of Excellence. “We discovered focal patches of disrupted development of these cortical layers in the majority of children with autism.”
The cortex has six distinct layers of specific types of brain cells that play an important role for processing information. However, key genetic markers were found to be missing in the children with autism. A disorganised collection of brain cells were present instead of distinct layers.
“This defect 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,” Courchesne said.
Developmental defects were found in the frontal and temporal cortex which help to explain why symptoms of autism vary widely across individuals with the disorder.
The frontal cortex is associated with higher order functions such as communication and social interaction. The temporal cortex is associated with comprehending language and deriving meaning. Disruptions in these cortical layers may underlie the symptoms that is most often displayed in autistic disorders.
“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,” said Courchesne. The patchy defects may help to explain why toddlers with autism show improvement with early remedy.
Understanding how genes affect brain development is critical, which could lead to earlier and new interventions to rewire connections to overcome early focal defects. Additional research will continue to be carried out to better understand autism which may eventually open new remedy options.
Reference:
1. Stoner, R. Chow, M et al (2014). ‘Patches of Disorganization in the Neocortex of Children with Autism’ , The New England Journal of Medicine, viewed 16th April 2014.
2. Chow, M. Boyle, M. et al (2014). ‘Patches of Cortical Layers Disrupted During Early Brain Development in Autism’ , University of California San Diego, viewed 16th April 2014.
