I know a pair of BFFs who both have ADD. Watching them try to have one conversation is quite eye opening. And a bit exhausting. I'm thinking back to every conversation I've ever had with a polymath or a person with ADD and asking myself, "man, is this what everyone else experienced listening to me?" No wonder the conversations always devolved to 1:1.
People with ADD understand why they shouldn't distract others, but theory and practice are poles apart, even by academic standards. Seeing tangents in text is a good indication they have an accurate diagnosis.