You might have smoked weed before, but I'm guessing u would hang with your buddies and smoke bong hits... recreationally. Lol...of course its going to be hard to concentrate with that amount of cannabis in your system.

Cannabinoids have a staying power in the brain. Some people notice if they smoke the night before, the next day it does help to calm the brain.

I've seen studies on the web, that try to say marijuana slows certain parts of your brain. If you want I can post something on it... But anyways, the same area that slows down, is shown in other studies to be over active in people with AD/HD

So it turns out, that yeah...for some people, they shouldn't be smoking, if they want to keep their non-add brains in tune. But for the add people, it actually helps them, because it helps calm the area that is too hyper.