I'm on concerta since last winter. It was making my stutter worst at first but I eventually got used to it and now it can actually help. My mind is less scattered (on a good day) so it's easier to notice and take control of my speech. ADHD is very different for different people. I am inatentive type and my struggle is primarily with motivation, organization and focus. I'm not hyperactive but I'd imagine that would make a stutter even worst, but I wouldn't know. Also, classical meditation is just impossible for me. I do walking meditations sometimes though which helps calm my mind.