I have sensitivity to both Aspartame and MSG. I can take Aspartame in tiny bits, like 1/2 can diet soda before I get sick. Same with MSG. I am also sensitive to saccharin 🙂 I break out in the hives with it, on top of all the other fun sickly feelings.
How it affects my PD I don’t know. I get too sick physically to care. And Aspartame makes me feel like my brain is sloshing around in my head.