I have a child on the autism spectrum with an IQ of 70, so on the cusp. If he had an average IQ he wuld be considered Aspergers, but he doesn't so he is PPD-NOS. I believe more children are diagnoses due to more information. My son wasn't diagnosed till 3rd grade after finally taking him to the Dan Marino center in Florida where we lived. It was at my insistence that he had more going on than ADHD, OCD, ODD, Anxiety disorder, speach/language delays. I did research on the internet that led me to getting him the proper evaluation. Support groups online has allowed parents to pick up on these issues more than in the past, educated parents seek proper diagnosis and are not put off to "oh this is just immaturity". I personally do not know anyone with an MR being given an autism diagnosis, two different things. People just don't say MR anymore anyway, I say LOW IQ or intellectual disability. I don't think any of it has anything to do with social status.