I was prescribed Adderall XR this past spring, and have been taking it on an as-needed basis (so typically Monday-Friday). I can't say I've noticed any significant positive or negative impact on my stutter personally. I think there have been studies that show that it can make stuttering worse, but don't quote me on that. It might have been tied to the theory that stuttering is caused by dopamine hyperactivity, since Adderall increases dopamine levels in your brain. I'd recommend looking into it, as it's a really interesting topic!