Very interesting. I worked with students with severe ADD. The nonmedical explanation why stimulants are effective for ADHD. It sounds like this might jibe with what you are saying, Adreno but need to go back and reread what you said. If I have misstated something below I haven't had my stimulant for the day, tea!! Keep in mind the below is the simplistic explanation for ADD. Think of a thermostat. Each of us has a "set point" where after a certain amount of stimulation our nervous system calms and we can screen out stimulation such as noise and concentrate Someone with ADD has a higher "set point" until the nervous system reaches this point. It's like a furnace that keeps running and running until the higher temperature is reached. Someone with ADD needs more stimulation before their nervous system is dampened and the person can screen out the extraneous input to the nervous system. Barb ETA Last time I looked and it was a long time ago, the distinction between ADHD and ADD went back to ADD. I don't know if that still stands today as the diagnostic terms changed over the years I taught.I I will look this up.