They range from severe cases of "classic" autism to the relatively mild form called Asperger's syndrome.
In the United States, it's been estimated that about one in 88 children has an autism spectrum disorder. This week, the U.S. Centers for Disease Control and Prevention revised that prevalence to as high as one in 50 children.
The new findings, reported in the journal Research in Autism Spectrum Disorders, are based on surveys of nearly 800 mothers of children with an autism spectrum disorder, 35 whose kids were free of autism but suffered from depression, and nearly 200 whose kids had neither disorder. The children ranged in age from 1 to 16, and the autism spectrum disorder cases ranged in severity.