There's A LOT of research into neurological differences between PWS and PWNS that may cause or contribute to stuttering. I tried to sum it up as simply as possible -- not easy to do -- in [this post](https://www.reddit.com/r/Stutter/comments/pl522u/neuropathology_why_stutterers_brains_produce/). There are also adaptations and attempted adaptations to stuttering. [This paper](https://academic.oup.com/brain/article/132/10/2747/330765) covers a lot on adaptations, including maladaptations. It's a bit technical, but hopefully my post above makes it easier to understand.