It's a label given to students who are driven to distraction by a critically flawed educational system and/or a boatload of irritating chemicals in the food supply so that the drug companies can sell more drugs to shut these kids up.
Obviously, merely getting kids a bit high to calm them down would be political suicide, but convincing people it's a "disease" that needs "medication" has been an excellent public relations maneuver. Witness yourself.
Most "medicines" for ADHD are central nervous system stimulants. Think cocaine and speed and meth, and you'll get it right. Now, I'm all for anyone who wants to use whatever drugs he wants to use them, with all the consequences that entails; but telling parents that their kids' brains are defective and need to be "medicated" with improved, longer-lasting versions of cocaine to "correct" their problem is massive betrayal.
Please stop spreading misinformation. We have Corinthian for that.