I mean, I agree and disagree: I do think that anxiety plays a huge role in it, but the root cause is dually a subconscious tightening of certain muscles in the neck and improper breathing when speaking, both of which I personally believe stutters are genetically predisposed to be more susceptible than most, especially the breathing. Like, I've always been a shallow breather despite a large lung capacity and running out of breath mid-stitter is a pain when you wish you'd've just taken a deeper breath a second ago. The anxiety is what makes it all more prominent and intense, as our minds begin to rush and we lose our usual subconsciously calm state. The neck stiffens ever so slightly, the rate of breathing becomes quicker and more shallow or ceases altogether without notice, both these conditions make it more difficult to manipulate the vocal chords like usual. *Which if I might add always bugs me to fucking death when I'm blocking. Like, I know the word (and next 20 I want to say, but I still have to act like I'm still thinking of this stupid word), I can spell the word, I can describe the mouth movements required to say the word, but can I say the word? Of course not.* This is why things like extending the syllable you're blocking on tends to help, if it doesn't just sound a little silly. It just helps to keep air flowing across the chords. But I also find that simply concentrating in the moment on relaxing the vocal chords and having plenty of air to help push out the word as you start helps a little. So, things like taking a quick medium-sized breath in and out when I'm stuck on a syllable helps reset the neck muscles and refresh the lungs. So, not really a "chemical" thing, but maybe you want to expound on that? And worth mentioning, I've rarely had someone overtly make fun of my stutter, definitely not outside of grade school. And even if someone were to, all it takes is a look and every witness would know that I could've gone off about it and would've had every right to, but I chose not to. People just get that you don't make fun of unchangeable things like that. That said, while people won't put you down verbally, they will definitely do so mentally. I don't mean like they're thinking you're less than or inferior in a totally negative sense, but the persona, energy, and charisma you are able to exude will naturally be affected. It may not sound like much, but that's what decides if your boss handing out raises thinks you're one of the good ol' boys or just background noise; whether you go to every class and lecture, or skip more and more because you dread having to verbally participate; or whether that cute girl from your Wednesday lab remembers that funny thing you said in class or how much you stuttered saying it; how the mannerisms in speaking you've developed to counteract the stuttering (e.g. elongating syllables, pausing in the middle of words, using "uh", "um", or "like" far too often, having a lead-in sound [mmmm, or ahhh] before saying something out of the blue) are interpreted by the uninformed ear. It really shapes how you become accustomed to approaching situations and people. So, I don't know, double-edged sword, I guess: either you practice like a fool or you don't and stay a fool. Like, with practice, you can overcome the anxiety and train yourself in good habits of verbal upkeep, but it'll be an uphill, no-glory, and exceedingly embarrassing battle the whole way with no real end in sight. Or just don't try at all, maybe it'll just go away. Sometimes it seriously does, it did for my uncle, though he was like, 20, and I'm 23 now, so I have little hope, but who knows.