I think chronic stuttering (child onset fluency disorder) has two main causes: 1. Disrupted flow of speech information from a supposed zone of conscious speech generation to the Broca's area (causes are practically unknown). 2. General neural hyperactivation of these two cortexes (also has a lot of causes). About a week ago I started taking Clonazepam - a powerful benzodiazepine аnticonvulsant. And an intencity of my stutters has been reduced by 50%. My psychotherapist (I live in Russia) is roughly said me the same two causes of stuttering and said that the pharmaceutical solution of the second cause is only temporary because of the nature of the drug. Earlier I tried several less powerfull drugs, but I didn't notice any major effects. The other solution is psychological - simply an exposure therapy - the more frequently and deeply you talk to strangers in weird situations - the less active your nervous system will become in these situations. And the only cure from the first cause of stuttering by the modern state of medicine - is to conscioisly feed Broca's area with less speech information. That means - speaking more slowly, rhythmically (to train with metronome), speaking in syllables or even letters. That's all.