I’m not entirely sure exactly what would differentiate different “levels” of autism under DSM IV, but if I remember correctly, the key difference between Asperger’s and high-functioning autism was whether or not there was a speech delay, people who had no delay got an AS diagnosis and people who did have a delay got an HFA diagnosis. So a speech delay alone would not mean that one is classified as “low-functioning.” I think I remember something about “with/without intellectual disability” being tacked on to the end, but I’m not certain about that, I’d have to look up how ID would affect a diagnosis. Under DSM V, Asperger’s is not a diagnosis, and ASD is given a “level” diagnosis (1, 2, or 3) based on how much support a person requires, which to the best of my knowledge does not directly take any speech delay or ID into consideration.
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Yet in my new wildness and freedom I almost welcome the bitterness of alienage. For although nepenthe has calmed me, I know always that I am an outsider; a stranger in this century and among those who are still men.
-H. P. Lovecraft, "The Outsider"