What if stutterers have 50-200% more dopamine *because* they are generally more stressed and nervous on a daily basis for a long term. It seems to me a more parsimonious explanation than the converse. > These studies increasingly hint that people who stammer do so because of connection faults in the speech-producing networks of their brain. However, the elephant in the room is whether these anomalies in the brain cause the stutter or whether 'natural' dysfluencies in early childhood create the anomalies in the developing brains of children who go on to stammer. >Kate Watkins admits that, at present, scientists simply cannot yet answer this chicken-and-egg conundrum. “The differences are there in young children close to the time that stammering starts, but most of the data acquired has been from adults who have stammered all their lives. So it is absolutely the case that stammering could cause the brain anomalies.” The only way to solve this mystery would be longitudinal studies over years or decades. https://www.stammering.org/speaking-out/article/science-stammering