Autism is associated with overgrowth in certain brain areas:
The study, led by scientists at University of North Carolina, Chapel Hill, and published in Nature, focused on 106 high-risk infants—those with autistic older siblings—and 42 low-risk babies. Researchers imaged the babies’ brains at 6, 12 and 24 months of age. Diagnoses of autism usually take place around age 2.
Of the 106 high-risk infants with brain scan at all three time points, 15 went on to develop autism. Their scans showed that by 12 months, there was significant overgrowth in several brain areas, including those involved in communication and in processing sensory information, compared with infants in the low-risk group and high-risk kids who weren’t later diagnosed with autism.