I have read the early studies about risperidone and olanzapine but from what I have seen the way they selected stutterers and tested for fluency is not that great. It seems most people who stutter do not necessarily stutter when alone or reading out loud but. Yet these clinical trials seemed to specifically select people with a severe stutter (people who stutter even when alone or reading out loud). They also tested improvements in fluency based on occurrence of stuttered words when reading out loud. Realistically rather sketchy clinical trial involving very small number of people.