There are parts of one that look like the other, so there can be diagnostic confusion. Which is to say that someone could be thought to have ADHD which turns out later is actually BP. (I suspect this is why it might look like it was the meds causing it, when in fact it might well have been just a misdiagnosis of what was already there. This is simply a thought that occurs to me as at least as likely a scenario.

Sometimes people have both (just for extra confusion! ) I don't know. BP is the obvious one in my case, but it turns out I seem to have ADD as well. My son was dx'd ADD, and is just entering the years when BP is most likely to make itself more clearly recognized. So who knows? His ADD dx seems beyond question, but will it turn out he also has BP? Could. There have been things through the years that have made me wonder. I don't know, but neither will I be surprised.

I don't think there is a connection per se, outside of some shared symptoms that is.

What was the question again?