Are you asking if ADHD makes people block more on words? Like the ADHD increases stuttering severity? If that's what your asking then I'm not sure of the answer because I haven't seen any research studies looking into this. I have both ADHD (diagnosed inattentive type) and stuttering runs in my family. I had a pretty severe stutter as a child that has reduced in severity since three years ago (when I was 25) so it's moderate or semi severe now. It may continue to reduce in severity as I age as thats typical for people who stutter because base levels of dompanine in the brain lower with age to and eventually reach neurotypical levels.