I know I'm a little late to the party, but I wanted to chime in with my 2 cents. I have a lot to say, so I'll try to keep this organized. First, I believe that ADD and ADHD are real disorders that affect a person's ability to focus (ADD) and is sometimes accompanied by hyperactivity (ADHD). However, this is a condition that is waaaaaay overdiagnosed.
There are diseases that only affect certain populations...think of sickle cell anemia that only affects African Americans, or tasax that only affect children of Eastern European Jewish descent. I do not however, think that this is the case with ADD or ADHD. I think the reason so many white boys are diagnosed with this condition has to do with culture and economics. Firstly, this is a mental illness. And while the stigma surrounding mental illness is not what it used to be, it still exists, and a lot of parents will deny that their child has a mental illness and not speak to their doctors about a lack of focus in their kids. (Of course, not every child who won't focus has this disorder, some/most of the time they're just being kids.) On the flip side, poor people (who in America are disproportionately people of color) do not have the resources to seek treatment, even if they wanted to, especially considering that this is not a life threatening disorder. So this situation narrows the segments of the population who are willing and able to seek treatment if they believe their child might have this disorder.
Now lets add big pharma to that equation. They put adds on tv that portray well to do white kids happily going about their lives on these drugs that will make them into docile obedient children. Now lets talk about the Individuals with Disabilities Education Act (IDEA). Before I go on, let me say that this is excellent and necessary legislation because there are students who need it and benefit from it. This law states, that the minute a student is diagnosed with a disablity, mental or physical, a host of special services kick in for them at school. Special accomodations are made such as modified homework assignments, special test conditions, special aides and tutors, as well as physical accomodations, as necessary. A team of professionals is assembled to come up with a plan for this one child's education. So there are tangible benefits that accompany a diagnosis. But it requires a lot of persistence and advocating on the part of the parents to ultimately obtain these benefits, and lets face it...some parents are more involved than others. And often, it's the parents who don't have to work 5 jobs to support their kids that can be this involved. It's a situation that leads to massive overdiagnosing in young white kids. Lets also consider that identifying and diagnosing mental illness is often not an exact science.
So yeah, it's totally a real thing, but so many times, kids who just have a lot of energy or act out in agressive ways (as boys are socialized to do more often than girls) are put on pills and told they have a disorder. A lot of times it just boys being boys. And while I agree that we most often see boys diagnosed with this, I have known many girls who also have this condition, while working in the schools. I also know adults who have this condition, but I think we're only now hearing about adult ADD because the psychology/psychiatry fields are only recently beginning to be taken seriously in our culture. 20 years ago, we didn't think of depression as a chronic condition with a medical treatment, but now we know differently and millions of people have better lives for it...big pharma: a blessing and a curse. Hope that makes sense. Just my opinion...albeit, a long winded one ;-)