I've never really gotten behind the belief that cannabis can cause these latent psychological disorders to pop up. On the contrary, I started after being "diagnosed" by some quack. Gave up talking to him after a few goes, started toking cannabis therapeutically... really helped. After a while I was feeling alright with less and less usage, so I stopped for a while. I think a lot of it depends how you consume it. If you're taking massive hits from dirty pipes, thick papers, etc... then you will obviously be consuming more carbon monoxide (doesn't it kill brain cells... sort of like holding your breathe too long... ? I can't call that one for sure). Anyways, I would say that it's probably just another anti-study. If even a study, and not just a story.