I am 16 and have done my homework on all this. I was diagnosed with ADD about 8 months ago. I am on straterra which is a non-stimulant medication. There has been a ton of controversy here about ritalin and things like that- well i will put it in lamens terms for everyone.
When you have ADD, your brain acts on EVERY, tiny little impulse. Its almost like you cant control the TV changing channels. What a stimulant does is it speeds up your central nervous system in a manner that makes it so your brain can catch these little impulses to calm your body down from hyperactivity and lack of focus. A depressant (stratera) just basically depresses you, calms you down, getting rid of all those impulses. They each have their advantages for every person.