Marijuana affects IQ and …

Addiction Psychologist Philadelphia

Finally there is some good research showing pot‘s effect on something other than short term memory and motivation which for a long time have been the only thing researchers have reasonably concluded are consequences of smoking dope. Other recent research found that pot can exacerbate a tendency towards mental illness and now that it affects IQ. While I don’t believe this knowledge will deter many young potheads because of their belief that they are invincible. 

http://well.blogs.nytimes.com/2012/08/27/early-marijuana-use-linked-to-to-i-q-loss/?smid=pl-share

https://www.jeremyfrankphd.com/drug-alcohol/marijuana/