I know I am not the only autistic person to have been considered slow or even mentally retarded. I also have read numerous online discussion groups in which people have posted about being diagnosed with OCD, ADD / ADHD, social anxiety, and even PTSD. I'm not sure how the Post Traumatic Stress Disorder fits with autism, but several HFA/ AS individuals report this as an initial diagnosis.
My wife is certain I was, am, and always will be HFA. My mannerism, my speech patterns (poor affect, or even inappropriate affect), and my stereotyped movements under stress are mere bits of the picture, as they say.
The new diagnosis was not based on any new evaluation results. My original (second grade) evaluations are little different from my undergraduate tests and those are both little different from the latest evaluation. Slow motor skills, good vocabulary, little comprehension of human motives. All that has changed over 30 years or so since my first evaluation is the label I'm given. (I am assuming I was seven or eight in the first grade.)
Maybe the labels do matter. The first time autism was suggest was many years ago, now. I just didn't want to pay for a full evaluation at the time. It's so much easier to run around and scream like I'm insane than to ponder what evaluations can reveal. Then again, my wife has known what I am like for much longer than I have.