And people keep talking about the "epidemic" but there is absolutely no evidence of an epidemic. There have always been autistic children, they were just categorized as 'retarded' until autism was broken out into a separate category around the time of WWII. And the definition of autism has expanded so much in the past ten years that there is probably very little if any actual increase, but if there is one it can't be quantified because you're comparing apples and oranges.
But what with parents with difficult children (and don't get me wrong, I'm one of them!) hoping for some sort of solid diagnosis, a definite cause, and a cure, and researchers hoping for a grant, there will always be an group of people who believe that the incidence of autism has wildly increased, and that vaccines are to blame.
My wife is a teacher, specialty developmental disabilities. She has seen good results, sometimes amazing results, with dietary changes etc. that would indicate that autism is not simply “retardation.” I hear what you are saying and statistics are hard to sort through . . . but . . . something seems to be going on with autism. It has the emotional withdrawal component that has nothing to do with being retarded or slow. Downs syndrome causes retardation, but those kids are socially outgoing. I’ve know a boy that was retarded because he was tangled up in the umbilical cord and it cut off oxygen when he was in the womb and he was in no way autistic; very outgoing and social.