Autism is a neurodevelopmental disorder affecting about one in 110 U.S. children, according to the Centers for Disease Control and Prevention. Though the disorder itself is well characterized, its cause has eluded researchers for decades. However, a new study recently published in the Journal of the American Medical Association brings us one step closer to understanding the possible mechanism by which autism manifests itself.
After analyzing postmortem brain tissue from seven boys with autism and comparing these samples to six boys without the disorder, researchers from the University of California-San Diego School of Medicine found that the autistic boys, on average, had 67 percent more brain neurons. The excess neurons were found specifically in the prefrontal cortex, which is an area of the brain responsible for complex thoughts and executive function. While developing children have about 1.16 billion neurons in this region, the study found that autistic children have about 1.94 billion.
Since neurons are generated only between weeks 10 and 20 of pregnancy, this finding suggests that whatever leads to autism must begin in utero. As ACSH’s Dr. Josh Bloom notes, “At least people can stop worrying about the vaccine-autism link and finally begin to understand that vaccines are not the culprit here.”
Though the current study was small and preliminary, it builds on earlier research that has also documented “brain overgrowth” in autistic children. Now the next step, according to study author Dr. Eric Courchesne, is to “find out what genes or what in utero, non-genetic conditions lead to an excess number of neurons.”
