I feel like my ADHD is pretty unexplored in my adulthood. I only know of it effecting me in one key area, and that's concentration. It took me forever to even catch it. But for the longest time my mind would drift while doing anything, including watching shows or movies. For so long I would feel clueless about what's going on in the plot and felt like I just wasn't smart enough to get it. =( But then somewhere around a decade ago I finally realized that it's not my intelligence, it's that my mind would go astray while watching things and miss portions of the show/movie, so of course I didn't understand everything!
I'm not sure exactly how I discovered I was doing it, but I eventually did. The key to me improving was recognizing exactly what tends to make my mind stray. I noticed that music was one of these things, if a background music elicited some kind of emotion in me, I could get lost on that and think of things that it made me feel and relate my experiences with that emotion, additionally if say I was rewatching a series from a long time ago and I had nostalgia for that music it would make my mind stray to happenings from my life when I first watched it. lol. Also plot points that I can relate to something in my life makes my mind stray, as does even a character looking like someone else. Stuff like that.
I don't have a perfect method of controlling it, and it still very much happens, but I catch it a lot more than I used to because I understand how and why it happens.
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Diagnosed with ADHD, Strongly Suspecting I'm also Autistic