Interesting. People with ADHD tend to have a lower dopamine baseline, and taking Vyvanse, which is a Dopamine agonist (increases Dopamine baseline) has been shown to improve fluency in stutterers with ADHD. Therefore, it’s definitely related to a dysregulation in Dopamine (and other) neurotransmitters in the speech motor networks in the brain. Some PWS may have a lower dopamine baseline, whereas others have a higher dopamine baseline. This is why medication which are dopamine agonists make stuttering worse for stutterers who inherently have a higher dopamine baseline. For me, GABA enhancing meds/supplements helps my fluency a lot as they “quieten dopamine hyperactivity” in my brain.