As someone with pretty bad ADHD... it's literally not something I can control. Most people who deal with me regularly are likely now used to it, but meeting new people it can definitely be off-putting.
It isn’t easy, but it’s possible, and over time it does get easier.
As someone who usually does not like to be interrupted, I would have no problem being interrupted this way. I prefer being understood as I speak so I can clarify and possibly adapt as we speak.
On that note, asking a clarifying question in the form of a statement of your current understanding of something is IME the best way to come to an understanding of complex discussion.
My brain is a stack, and most people are queues, so if I don’t write it down, I have already forgotten it; but that’s only really important for interruptions that lead to tangents.
Interrupts from an active, engaged listener are usually received positively.