My son, who is nearly 34 years old was dx'd early on. The one thing I found that really helped him was removing sugar and all things that easily became sugar when eaten from his diet. I suspect a lot of ADHD is too much processed foods. But in his case, I think he does have a physical aspect of the frontal lobe that will never be the same as other "normal" people.

There are a lot of things that can contribute to the symptoms that are associated with ADHD, making it appear a person has it. But if those things are removed and the behavior continues, I think it really is a physical part of the brain.