ADHD is simply the lack of ability to control attention. There are drugs that work short-term, however long-term only methods of coping are really effective.
After reading everyone posts below, I figured I would direct you to my startup:
The startup (just applied to YC) that my team and I are working on actually addresses this issue using something called neurofeedback therapy:
Effectively, your mind is like a programmable computer. Once you learn to recognize when you start losing focus, it's possible to program it (over time) to do something different. The idea being, neurofeedback therapy lets people better understand themselves and in-turn cope better.
After the brain has been reprogrammed it stays that way long-term (unless something else reprograms it).
If you are interested in reading more about neurofeedback, here's a literature overview: