Hi there, I have been doing some extensive research on stuttering and pharmacology. Most researchers agree that dopamine is the main part involved in stuttering as stuttering most likely comes from underactivation of the Broca’s Area. Anti-psychotics (Dopamine Antagonists) have shown a lot of evidence as to treating stuttering (I will say I noticed a 90% decrease in my stutter when I tried it). However, these can carry a lot of risks including cognitive decline. Atypical anti-psychotics are being researched which have minimal side effects while also focusing more on a specific subreceptor of Dopamine which can treat stuttering. Now, dopamine is much more complex that just increasing and decreasing it. I even wrote an article about a stuttering treatment using tDCS. I have personally found that stimulants make my stutter better to manage (which typically, wouldn’t make sense since stimulants tend to have the opposite effect on dopamine compared to anti-psychotics). Now on to GABA, there isn’t a lot of research saying GABA is involved but it could still e related. Benzos most likely work by just decreasing anxiety which in turn, can help minimize your stuttering. With that being said, Xanax has some downstream dopamine effects so it is possible that plays a part in it as well. Phenibut is also interesting and is used in Russia to treat stuttering (although it seemed to make mine worse; I typically get worse from GABA related drug with my stutter while others seem to benefit from it; your mileage may vary). One that does have an effect on Gaba though and still has treated my stuttering is known as Aniracetam and I think it is a really interesting compound to try out. Feel free to write me / post a response if you need any help. I also am trying to collect data from people on how their stutter is affected by pharmaceutical substances / nootropics so if anyone has that, feel free to write me too.