I think it's the Ritalin, not the ADD, that's the problem. IIRC, long term use of Ritalin prevents individuals from joining the military. It seems to cause permanent, physical changes in the brain, especially if taken during the formative years.
Not exactly. It seems if a kid is off his meds and is able to function without them for over a year, keep a job or in school, and pass the tests then they can be considered for enlistment (Source: http://www.dbpeds.org/section/fall98/adhd_military.html ). But I think your correct about how the meds (and Ritalin is only on of many prescribed at this point) messes with their heads. I known few people who didn't have some issues due not learning coping mechanism to deal with ADHD and permanent changes to the brain (I cannot prove the second one, it's just experience with many friends who did come off).
Either way, there are pro and cons to someone with actual ADHD being used in the military. There is theory I've read about that people with ADHD are natural hunters because there is a lack of ability to choose to take in, so they take in everything at once and are considered more aware (therefore unable to focus. There are also two other states, hyperfocus and brainfog, which float intermediately between if someone is truely ADHD). However, there is the down side where your confronted with someone screaming in your face and you can't even hear them cause you can't concentrate on them cause your ability to hear has been shot at that point due to all the directions you've been trying to pay attention to. Point being if ADHD kid is trained right, they'll do well, they may just be sent back in WOT a bit, which probably is good.