I've heard a nice description of ADHD being both the most under and over diagnosed issue at the same time. Since it's mostly based on self-reporting, it's easy to get on the meds if you want to, or easy to pin on an issue someone may be having, as a quick solution. On the other hand, for various reasons high functioning people will keep on going and try to deal with it daily until they run into some roadblocks. It took me over 30 years to get diagnosed, but really I should've done it in primary school already. (There was minimal awareness then)