giftedticcyhyper -
I have no idea on the percentage, but I will ditto the sentiment. DS saw a psychologist - he said that there would be no way to tell if DS was ADHD or just gifted because a bored gifted kid will act like a bored gifted kid with ADHD! He said that if we could get DS in a challenging environment and he still had the same signs, then ADHD would be more likely.
Supposedly, you could always do a drug test (I don't think this is a good idea). A truly ADHD person is supposed to be depressed (read: calmed) by stimulants while others would be stimulated.
