Extra Brain cells show possible prenatal origin, study says

Researchers found children with autism have more brain cells in the prefrontal cortex, which deals with communication and emotional development, than children who do not have autism. This study suggests that autism in children begins during pregnancy as cells in this area of the brain develop during the second trimester.

Dr. Eric Courchesne of the University of California San Diego Autism Center Of Excellence and his colleagues focused on the prefrontal cortex because this area of the brain was thought to grow too quickly and too large in children with autism. The team found that not only did children with autism have a greater number of brain cells in that area, but their brains also weighed more than children who do not have autism.

Scientists have deliberated for years whether autism has a prenatal origin, finding dozen of genes that may increase the risk of autism and possible environmental factors while in the womb. However, genetic causes explain only 10 to 20 percent of autism cases.

The team conducted research by counting the number of brain cells in tissue from seven boys with autism who has died and six boys who did not have autism who died.

Courchesne said the prefrontal cortex is the art of the brain used for social, emotional and communication functions, three areas in which children who meet the criteria for autism spectrum disorder have problems.

The findings of this study show that the origins of autism start very early, said Lizabeth Romanski of the University of Rochester Medical Center, who did not participate in this study.

“The generation of new neurons, what we call proliferation, occurs prenatally during the second trimester,” she said.

As this is the time when neurons are being created, Romanski said this finding of increased neurons in children with autism suggest something occurred prenatally to change the way the brain develops.

Courchesne said he believes that the study of prenatal life and mechanisms during that time will lead to an understanding of where autism comes from.