My son was 10 when I finally took him into a specialist to have him checked for ADD. It was only because at that time he started falling behind in school because the course work changed, and it was a critical time for him to be able to learn those things that will carry over into 5th and 6th and middle school.
I always knew he had issues, and suspected ADD, but refused to have him diagnosed as we were getting along fine with the behavior modifications at home. But I wanted to do what was right for him educationally, and didn't want him to frustrated and end up dropping out of highschool years on down the road like his Dad did.
We put him on Strattera, and it works for him, his concentration levels are back on track. Don't get me wrong, he's still the typical ADD kid, and it's REALLY frustrating at times, but he's happier and isn't struggling to keep up. He makes A's and B's.
He also had severe milk allergies as a baby, and has asthma, I don't know if there is a connection, but we moderated his diet and follow it fairly strictly.
ALso, we find that a REWARD system works alot better than punishment for most things. For instance: If you take your medicine for 1 week without forgetting a day, you get 30 minutes of video game time on Friday.
If you do your chores for a week without missing a day, you get to go to Youth Group on Sunday evening.(It's considered extra curricular, and not included with Church)
Pick out things he can reasonably do for his age, and reward him for doing it.
Be consistant.
Have consequences that are short and to the point. Grounding for more than a day or two doesn't work well cause they forget why they are even in trouble 1/2 the time if it's longer than that.
Hope some of these help.