Eek! I hope not, I'm only 36, although it's possible.
I visited my Mum yesterday and she noticed I was talking way too fast and worrying about everything - she thought I was in an odd mood, so it's possible the Amantadine revved me up. As today wore on I felt calmer and calmer again, the nervous feeling went. I'm going to leave it a few days and try it again, and if the same thing happens I think it looks like Amantadine.