You are so right about brain chemistry. We are different from fluent individuals. I also believe that external factors can potentiate stuttering such as adverse childhood experiences, (abuse) adult trauma, medical conditions such as stroke and TBIs, and more. I'm a 78f with mild stuttering, I'm even fluent on the phone and in casual conversation but, ask me to explain anything I stutter severely. As far as my stuttering currently, I have accepted the condition and have recently turned down an opportunity to access speech-language therapy at our local medical school. My life has been very fortunate despite my stutter. I enjoyed a 54-year marriage to an amazing man, our children are happy and productive. Now, radical acceptance makes the most sense. The research into brain physiology needs to expand. Medication-mediated treatment has to be a priority. Even as a patient of Dr. Maguire, nothing could be done yet without any useful medication. Even he recommends speech and psychological therapy…and acceptance. Perhaps with AI physiological answers and medication treatment will advance.