[tpm]

It's anecdotal - you have no way to know what would happen otherwise. I have seen plenty of young people smoke weed in their teens while gradually stoppping later and leading completely 'normal' lives, while a few didn't stop and went to heavy polydrug abuse etc. What exactly does that say about weed? Not much I'm afraid.

Similarly, I know of several persons that went schizophrenic after car accidents, but were the car accidents the cause?