Stuttering is thought to be related to dopamine, and Olanzapine blocks dopamine receptors. My theory: It's possible that stuttering is caused by a dopamine imbalance, and therefore could be caused by both high or low dopamine. This could explain why blocking Olanzapine could result in reduced stuttering in some and increased stuttering in others. [It is worth noting that olanzapine, in addition to being used in the treatment of stuttering, may itself cause stuttering as a side effect.](https://arsiv.dusunenadamdergisi.org/ing/fArticledetailsb985.html?MkID=1302#:~:text=Our%20case%20and%20others%20found,stuttering%20as%20a%20side%20effect.)