I don't know how much over-diagnosis happens but there does seem to be a considerable number of young children who "outgrow" it--probably never had it in the first place. By 5, I would think a diagnosis would be more reliable but still be careful. There was a place I wanted to take DS based on the school's recommendation and the pediatrician refused to give me a referral saying "they diagnose everyone with autism". She sent me to the neuropsych at the university instead. And he made similar comments. we filled out rating scales plus there were a couple tests looking at affect recognition (reading emotions on people's faces?) and "theory of mind", all of which he did fine on.
