Hard science, big samples, control groups.
Smoking cannabis makes you retarded and lowers your IQ permanently
Teens who smoke dope grow up to be morons with no saving throw against brain damage.
I always knew it! It doesn't matter what anybody ever said to me. I knew it!
I said it in the military and everybody in the room laughed at me.
I said it at work in the lunchroom and everybody laughed at me.
I said it on usenet and everybody on the thread laughed at me.
I said it on forums and on BBS lists and everybody there laughed at me.
I've said it to people with joints hanging out of their mouths and they laughed at me as they inhaled.
I've said it to people with the bong in front of them.
They've said to me, you're just afraid. You're scared of drugs. What harm could it do you to try a little?
I've told them, it's because I've got a lot to lose. Ten points off your IQ won't matter much either way and nobody will be able to tell the difference. Ten points off my IQ I can never get back is a really big deal. I will be damaged goods. God gave me my neurochemistry and if I deliberately harm it I will have committed a sin. It's all I can do to get my brain to stay sharp as it is, the last thing I need to do is smoke dope.
One could make the argument that my sleep cycles and depression have done me as much brain damage as smoking dope might've done and they'd probably be right. The thing is, all those things have been outside my control and I have not wanted these afflictions, they were forced on me.
Another thing is, some mornings after 10 hours of sleep I feel like my old self again. With these drugs I don't think it works that way. This kind of brain damage doesn't get fixed by some rest or vitamins.