New research shows Autism starts prior to birth. Autism begins when certain brain cells fail to properly mature within the womb, according to scientists.
Brain tissue taken from children who died and had autism revealed patches of disorganization in the cortex, a thin sheet of cells that’s critical for learning and memory, researchers report in the New England Journal of Medicine. Tissue samples taken from children without autism didn’t have those characteristic patches.
Most autism studies have been done using imaging technology, such as an MRI, only a handful have been based on an analysis of brain tissue, which mostly were taken from adults.
Organization of the cortex begins in the second trimester of pregnancy. “So something must have gone wrong at or before that time,” says Eric Courchesne, an author of the paper and director of the Autism Center of Excellence at the University of California, San Diego.
“These patches of disorganized cortex are patches where cell types have failed to develop,” he said. “This indicates this must have happened in fetal life when the brain is setting up neural cell types, neural connections and neural layers.”
By the second trimester, fetal brain cells are making complex connections, the scientists said. At this point, the cortex develops into six layers, each with its own specific types of cells, assembly patterns and connections that perform unique roles in processing information.
But in the children with autism, “there are patches in which specific cells in specific layers seem to be missing,” Courchesne says. So instead of distinct layers, there are disorganized collections of brain cells.
These patches of disorganized cortex would have different effects on the brain depending on where they occur and how many there are, Courchesne says. Which could help explain why the symptoms of autism vary so much.
“The next step is to investigate the cause of these abnormalities and if anything can be done about it,” said Ed Lein, an investigator on the study from the Allen Institute for Brain Science.
“The broader implication is now we have more evidence that brain changes early in life are very important for understanding autism, and it helps make the case that we have to start earlier to understand causative factors,” said Dan Smith, senior director for discovery and research at Autism Speaks, an advocacy group based in New York.
“We need to expand on findings like this study to understand whether there are biological markers that we can detect before we detect behavioral changes,” Smith said in a telephone interview to Bloomberg.
Courchesne said bigger studies that include more subjects and genetic markers, as well as more extensive brain mapping will be needed to confirm the findings or to find potential triggers that cause the brain differences.
“Our panel had only 25” gene markers, “the largest panel ever used, but it’s not enough,” he said. “Even though we had 12,000 slides, that still isn’t sufficient.”
About 1 in 88 children in the U.S. have one of the autistic spectrum disorders, which include classic autism and a mild form, Asperger syndrome.