I'd like to hear an opinion of someone who's pro at psychiatry about this crazy dude that hangs out at our university. He's about 50 years old who goes to random lectures and constantly mumbles stuff that doesn't make sense. Sometimes he asks random people questions about homework or touches people's backs or shoulders. He also handles other people's belongings when they're not around, although I don't know if he steals anything.

So yeah, I'm wondering what kind of mental disorder causes this, apparently he's not dangerous because he's not locked up, thanks!

There is not enough information for anyone to make even a "best guess" diagnosis He could just be an eccentric individual, he could be schizophrenic, he could be mentally challenged. Yuo will have to be more specific and provide as much detail as possible to get an educated guess. and that is all it will be.

I guess I don't have enough information, thank you for the answer.