Tangential, and not an answer to your question, but if you're like me, you will be fascinated to learn that there is a drug (MPPP, synthetic opiate) that if cooked incorrectly yields "MPTP"[1] which will give you Parkinsons. As in, forever. You take this drug (at any age) and then you have Parkinsons for the rest of your life.
1. There is one substance that rewrites your mind.
2. There is more than one substance that rewrites your mind.
Are very different postulates.