Its a matter of finding the right balance. My depression is dopamine related. Too little dopamine is responsible for low mood, lack of motivation, energy, anhedonia. Now when you realise that D2 overactivity can worsen your stuttering things are getting to confuse, in fact its much more complicated than we're assuming. Our stuttering is different from person to person. For example amphetamine makes my speech little bit more fluent, but its an direct dopamine releaser, though.