This is probably a little out there. Bear with me for a moment, as I expound on a theory entirely without any kind of real educated basis
Has it occured to anyone that ADHD (originally referred to by neuroligists as two seperate disorders: Attention Defecit Disorder, and Hyperactivity Disorder) may just be a haphazard coping mechanism that our brains have devised in order to handle the massive amounts of information that the modern world throws at us on a day to day basis?
Consider: ADHD is marked by an inability to concentrate on one single task at a time, a tendency to daydream, a state of mental and physical high gear, and generally not fitting in seamlessly with the rest of the teaming masses of future proles surrounding a child in his or her classroom.
Is it not possible that, in fact, this is evidence of mental multitasking, at the expense of inability to focus on only one thing at a time? Perhaps the hyperactivity is just a way to deal with an environment that moves at an equally hyperactive pace?
Evolution is never seamless. It is always sloppy; trial-and-error. As someone diagnosed with ADHD as a child, I have begun to wonder -- more and more -- if ADHD is not a disorder, but an adaptation.
Something to think about