Is adult-onset stammer a thing? Can it be cured?

Is adult-onset stammer a thing? Can it be cured? When I was younger, I did not stutter. The first time I noticed my stutter was in class 8, when I tried to say "l-l-l-literature". For a few years it was just the letter "L". During A Levels it got worse, progressing to "p", "k" etc, and at the end of A2 I couldn't speak a full sentence fluently. Now I stammer on every damn letter, especially letters that need force to be sounded like "t" and "p". The situation I'm in or speed of talking don't matter; yesterday I was reading out loud to myself and I *still* stammered on a word, even though it wasn't even on my mind. Could this "adult-onset" stammer be cured gradually over time just the way it developed?