This is not new news, but bears repeating: the human brain is not fully, fully developed until the age of about 25. Go figure.
My theory is that teenagers who have any sense, upon being told this fact, ought not want to do things chemically to their brains, at least while it is being formed.
Here’s a quote, from an interview with a neuroscientist:
the brain, especially the front part, doesn’t mature until age 25 or 30. We joke that the car rental companies had the best neuroscientists.
You can’t rent a car until you are 25 years old. How did the car rental car companies know this? Probably from accident statistics.