Autism Begins Before the Brain is Fully Developed, Study Finds

A new study shows that autism begins very early in life, even before the brain is completely developed.

The study, conducted by researchers at the University of California, San Diego School of Medicine and the Allen Institute for Brain Science, found that disruption in certain regions of the cortical layer might be linked to autism.

The cerebral cortex covers the outer part of the brain. It is also known as the gray region of the brain and is associated with intelligence, personality and motor function.

"Building a baby's brain during pregnancy involves creating a cortex that contains six layers," Eric Courchesne, PhD, professor of neurosciences and director of the Autism Center of Excellence at UC San Diego said in a news release. "We discovered focal patches of disrupted development of these cortical layers in the majority of children with autism."

Autism Spectrum Disorders are a group of brain disorders that can cause significant social, communication and behavioral problems. Previous research has shown that both genes and environment raise autism risk. Several studies on the condition, especially those looking at the pathology, have used adult brains and worked backwards. In this study, researchers used post-mortem brain tissue of children aged between two and 15 years.

Courchesne and colleagues looked at 25 genes in the brains of children with and without autism. The team analyzed the genetic markers known to develop the cortex.

Researchers created 3D model of the brains using data from the Allen Brain Atlas, as well as the BrainSpan Atlas of the Developing Human Brain. The model helped researchers see where the wiring in the cortex was disrupted in children with autism.

Each cortical layer has a specific network made by specific type of brain cells. These different neuronal networks later combine to perform various information processing tasks. According to the researchers, it is possible to observe genetic markers associated with early cortical development.

The team found that key genetic markers of cortical development were absent in children with autism. The damage wasn't uniform and was especially seen in the frontal and the temporal cortex, probably showing why different brain systems are affected by autism.

The frontal cortex is a hub for communication and interpreting social cues while the temporal cortex is associated with language. Changes in the development of these parts could explain why autistic children often face behavioral problems. The visual cortex, which isn't affected in autistic children, showed no sign of disruption.

"The fact that we were able to find these patches is remarkable, given that the cortex is roughly the size of the surface of a basketball, and we only examined pieces of tissue the size of a pencil eraser," said Ed S. Lein, PhD, of the Allen Institute for Brain Science in Seattle. "This suggests that these abnormalities are quite pervasive across the surface of the cortex."

These patchy defects, according to researchers, show that the condition isn't uniform and that some children might cope with the symptoms of the disease by forming different kinds of brain networks.

The study is published in the journal New England Journal of Medicine.