Yeah, it could be Parkinsons. Maybe he suffered a stroke recently. My grandpa had a stroke a couple years ago and he's still working on his mobility skills. Maybe it's Tourettes. Maybe he was in some sort of accident in the past that caused some nerve damage. God, there are so many other reasons for why a person is twitching.

But no, it has to be drugs, because that shows how dark and dangerous LKH's world is.