As a person with ADHD (diagnosed in my twenties while in college of all places, around 10 years ago), I have to admit that I only scanned/skimmed/scrolled through the OP and following replies. One of the tendencies of ADHD people is that we're very visually oriented, so too much text without distinct or colorful formatting can be hard to focus on...

As such, it's possible that what I'm about to say and offer is redundant (if so, my apologies!).

Firstly, there are definitely valid issues when it comes to both overdiagnosing and underdiagnosing ADD/ADHD. But ADHD is very real, is often far more obnoxious for the ADHD person than anyone around them (biased!), and unfortunately, because it's not visually obvious from sight alone is difficult for the ADHD person and those around them to equally understand.

There are specific and particular criteria required for valid diagnoses, which I believe was described and defined in the replies above.

But when I research anything, I like visual media, animations, videos, etc. So, I am going to post a thread with a list of videos on youtube that are ADHD-related, which have been VITAL in helping me better understand myself, and which I've shared with friends and family who want to understand me better, too.
(originally, was going to include here, but it could be helpful to others, so wanted to make it a bit more available in this section of the forums)... I hope that's okay!

I hope you'll take a look, and that it helps you and your friend better understand and clarify this new ADHD thing.

- Scienna