I think that with my stuttering atleast it might be caused by a neurosteroid imbalance. I notice as I got older into my 30s I stutter alot worse..which sucks because I thought it would get better with age. I also felt more mentally sharp in my early to mid 20s..its something to think about for sure. Maybe people stutter for different reasons but I tend to think stutterers that have allt of blocks & anxiety are more prone to ptsd like myself for example. It all seems like a pattern with stutterers but who really knows at the end of the day.