Hey! I have a mainly anxiety based stutter though I imagine there is a genetic component to it as well such as the lack of blood flow to the broca you mention. I stuttered as a kid and saw the schools speech therapist and then stopped stuttering for the most part until, like you, I became aware of it around age 22 after something traumatic happened in my life that lowered my self-confidence (was cheated on). I am now age 25 and have seen a speech therapist, taken anti anxiety medication (id recommend avoiding this if possible), joined a local stuttering support group, read books on the subject, etc. What has helped me to stop stuttering the most are 3 main things: exposure, mindset and maintenance. I have found that blocking is my worst enemy, when I stutter I have to just slowly stutter over the word while maintaining eye contact with the other person and NOT develop any ticks, it feels right to twitch your head or another part of your body while stuttering. don't do this!! as it is hard to break this once it happens. It also feels right to block, what I mean by this is slurring over a word, using similar words to substitute a word you feel like you are about to stutter on, avoiding words altogether, or just hitting a wall because you are so ah-ah-ah-ah-afraid to stutter over the word. U have to grow balls of steel and just stare someone straight in the eye while you stu-stu-stu-stutter over your words. Dont feel embarrassed about the stutter, just do it. the more you do it the easier it gets. the first time is so so soo hard, but i promise after you start doing it regularly it becomes very easy to do. It is also important to laugh at your stutter. your mindset about it HAS TO BE positive. it cannot be a negative thing in your mind. Another tip: If you stutter a lot over a word while talking with someone just make a joke about it! Life is a meaningless void of existence anyway dont take it so seriously! Once you have mastered these things you will find your stutter beginning to disappear! This is the danger zone! You stop stuttering for awhile, forget about the anxiety you used to feel about it, start to stutter again and BAM anxiety! and the cycle starts again. To stop the cycle from repeating itself you have to intentionally stutter over words the rest of your life. Nothing huge just sm-ah-ah-ah-ah-all stutters he-he-hear and there. Stutter slow and controlled and DO NOT shy away from it, tackle it HEAD ON and make it your bitch! I also found that a sugar rush or excess caffeine or alcohol can make your techniques more difficult to practice so avoid these in excess until you are in the maintenance phase. exercise, proper diet and sleep are also very important to keeping your mind sharp and positive. Find that fire and passion and make it happen! Good luck brother!