Although the exact cause or causes of autism are still unknown, new research from the University of California, San Diego School of Medicine and the Allen Institute for Brain Science as published in the New England Journal of Medicine provides evidence that the developmental disorder begins during pregnancy.
Autism is a developmental disorder that manifests during the first three years of life. The disorder is characterized by impaired social interaction and verbal and non-verbal communication and by restricted, repetitive, or stereotyped behavior. Approximately one in 88 children is diagnosed with an autism spectrum disorder (ASD).
For the present study, the researchers analyzed 25 genes in postmortem brain tissue of children with and without autism, including genes that serve as biomarkers for brain cell types in different layers of the cortex. Such genes have been implicated in autism and several control genes. The study builds on previous research that used the brain tissue of adults with autism in an attempt to extrapolate development.
The researchers found that key genetic markers across multiple layers of brain cells were missing in the brains of the children with autism.
The following video illustrates the research findings:
Explains Eric Courchesne, PhD:
“Building a baby’s brain during pregnancy involves creating a cortex that contains six layers. We discovered focal patches of disrupted development of these cortical layers in the majority of children with autism. 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.”
Equally as important as the evidence of developmental disruption in children with autism is that defects appear in “focal patches,” particularly around the frontal and temporal cortex. The focus of the defects the differences in functional systems among individuals with autism.
States Ed S. Lein, PhD, of the Allen Institute for Brain Science:
“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. This suggests that these abnormalities are quite pervasive across the surface of the cortex.”
Adds Dr. Courchesne, “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.”
The patch-like nature of the defects may also explain how some toddlers with autism show improved symptoms with early treatment. The researchers believe that the focal patches supports the theory that the brain may be able to rewire neural connections to avoid defects.
The findings of the study may help researchers work with brain rewiring to develop new treatments and therapies for autism.
Another recent study also found strong evidence that exposure to environmental toxins during pregnancy plays a role in the development of autism.
Autism Begins in the Womb, According to a New Study: http://www.medicalnewstoday.com/articles/274655.php
Patches of Disorganization in the Neocortex of Children with Autism: http://www.nejm.org/doi/full/10.1056/NEJMoa1307491?query=featured_home&&
Autism Begins in the Womb: http://www.freeimages.com/photo/676877