There is some anecdotal evidence that psychedelics may help. They are slowly but surely being tested on people and at start they will be used for more severe disorders, but I hope eventually they'll try to use it for stuttering. I think that there is a bubble we stutterers live in and people outside don't know and don't care about and that's big reason for lack of progress in speech improvement. Psychedelics and stuttering can help eachother to raise awareness hopefully.