Studies show people with ADHD lack a specialized area of their brains for handling working memory, unlike non-ADHD people. This means that for me, my brain handles working memory tasks analogously to how blind people can learn to "see" with their tongues -- I have to marshal unrelated brain areas to try to make up the difference.
I don't qualify as ADHD, but I've found that I do the same, substituting my auditory memory for working memory. Apparently it's much easier for me to keep a train of thought on the rails if I use my language processor for additional short-term storage. I didn't even realize I did this, until people started telling me that I shouldn't talk out loud during written exams.
This may be miles off from your experience, it just lit a spark of recognition.