I have ADHD and I do this. I don't want to. I just do it without thinking about it. It's because if I have a thought worth sharing, I want to do it NOW... there's always the possibility I might forget it before I've had the chance to share it.

Also when I talk to someone who has ADHD it might sound strange to neurotypical people. The discussions are much faster and also less - well, I don't want to call it less boring. They are more exciting, but it does not mean that discussions with neurotypical people are boring.