In the mid 1980's, I noticed our local school's handicapped population had changed from mostly educable and trainable mentally retarded to a high number of emotionally handicapped and autistic students. These populations have increased greatly over the past two decades. I asked our special education school principal if she had noticed the change, and how she explained it. She said that many children who might have been educable and trainable mentally retarded were aborted. She attributed much of the rapid increase in emotionally handicapped and autistic students to genetic abnormalities caused by parents' drug use. (Please don't flame the messenger).
Your comment is interesting.
I often wondered why the "special ed" cases nowadays seem so extreme. It's certainly a far cry from my schooldays, back in the Stone Age (talk about Neanderthals), when you might have had a kid who was a bit "off." A lot of them nowadays seem uncontrollable.