Unfortunately it's hard to prove to someone who can't experience it that ADD exists. Its symptoms are too easy to explained away with quite a few different theories. Unfortunately ADD is not just another overmedicalized normal condition. Even though far too many well intentioned people who can't understand assert that it is.
I do have problems with anxiety and depression, and they are not untreated. They are related to but distinct from ADD.
And mindfulness can help, like it can almost anything, because it's a tool for controlling your thoughts. This can be directed as willpower. While not without side-effects, willpower can overcome most of the problems associated with ADD in high enough doses.
I believe that in the future, the medical community will have a better understanding of the many things that can cause ADD, and the diagnosis of "primary ADD" will mostly be replaced by other diagnoses.
I have no idea if most of these will be depression/anxiety diagnoses or not. I was just talking about my own, very limited experience.
> Unfortunately ADD is not just another overmedicalized normal condition.
I actually do think it might be overmedicalized in children. I grew up with many children who would be diagnosed with it today, but weren't at the time. Whether they had it or not, they grew into functioning adults without ADD.