I have searched a little bit on PubMed , research show low ATP production in the speech area , less blood flow. That's why cardio and strength training work. Also what therapy have you tried? Benfotiamine and magnesium help me very much because they increase ATP production When my ferritin was low i couldn't speak at all, now it's around 150 and my speech is much better . B12 B9 deficiency play a huge role too. Nutrition is very important for us, do you have low GABA or low serotonin or LOW DOPAMINE?