1 in 68 children have been diagnosed with autism in the US. The risk increases to 1 in 5 for those children that have an affected sibling.
Researchers at UNC Chapel Hill used MRI to evaluate the brains of high risk infants (those with a sibling with ASD). Overall brain volume, surface area and thickness of the cerebral cortex in select areas were measured. They discovered an overgrowth of cortical surface area in infants later diagnosed with autism. Using an algorithm they developed researchers were able to predict with near certainty which infants would later go on to develop autism by age 2. Further, cortical thickness was found to remain unchanged but the surface area of the brain increased at a higher rate than normal between 6 and 12 months of age. This expansion is believed to be due to an increase in neural progenitor cells (immature pre-neurons). Additionally, only the social symptoms of autism were found to be a consequence of these brain changes not the repetitive behaviors.
The study is important in that the earlier we begin behavioral therapy in autism the greater the chance of limiting its adverse consequences.
Nature 542, 348-351 (16 Feb 2017)