A small study in children who died found unusual brain development was common in autistic kids but not in others. The preliminary research bolsters evidence that something before birth might cause autism, or at least some cases of it.
The abnormalities were in brain regions important for regulating social functioning, emotions and communication. Those can troublesome for autistic children.
They were seen in 10 of 11 children with autism, but only one of 11 other kids. The brains were donated to science after death from causes including drowning.
The researchers say genetics and some other factor might have caused the abnormalities.
Researchers from the University of California, San Diego, led the study. It was published in Thursday's New England Journal of Medicine.