I can only speak from personal experience, which is of course limited. I smoked occasionally in my 20s, but not since (I'm middle-aged now). I've been friends and acquaintances with many people that smoke a lot. I see a trend among these people - not necessarily schizophrenia (I'm not a psychologist and probably wouldn't even notice a mild case) - but instead a consistent arrogance and self-importance. It's peculiar…
I could certainly be accused of haughtiness when someone made a snide remark about me using marijuana. This is because I got fed up with arrogant people shitting on me when they found out I use it. In my experience it is those who love to flout their sense of superiority by shitting on users who are arrogant. But shit can flow both ways and when I'd point out that they too use "drugs" they'd get very defensive. Back…
Well, it does measurably decrease IQ. And at least in teens, this reduction seems like it may be permanent.