Oddly enough my brother in law (33) also has ADHD and was recently prescribed Ritalin. In terms if helping him focus he said it was amazing and he loves it. Speaking to my mother in law recently she said that he stutters so much less without it. Keeping in mind that I never thought of him as someone who stutters as he always seems very fluent in his speech. Me on the other hand I'm more noticeable with my stutter. So it's weird to hear how you have had the opposite experience. I had recently read that a recent study trialed people who stutter with Risperidone and there seemed to be some positive effects but I think they need more research to conclude anything.