Personally, I don't think there HAS been any dramatic rise in Autism. I think there have been way more diagnosing it. And way more "syndromes" on the spectrum.
For example, in the special ed preschool I worked in, staff would work VERY hard to NAME any given issue a child had, just to get him IN the program where the child could get the help they need. If they couldn't FIND a name, the child might be denied enrollment and miss out on all the help that was available to them at our school.
Also, the more kids we had officially on the spectrum, the more funding we got.
And every single one of those blurry diagnoses go towards the statistics you read that show Autism skyrocketing.
This is not a BAD thing, there is SOOOO much help for kids who need it now, as opposed to even just a decade ago (much less a generation or two). So what difference does it make what we CALL the thing?
Least that my theory.
:)