--- ---  # Repeated Pot Use Linked to Lower IQ ## Video: Inside the World of Medical Marijuana for Kids [Watch (HLS stream): Inside the World of Medical Marijuana for Kids](https://cdn.jwplayer.com/manifests/6Ic4KUCK.m3u8) (16:16)  _Published 2014-10-21. The story of a family's illegal cross-country drive to transport marijuana oil for their epileptic 3-year-old daughter. A look inside the quasi-legal, science free world of medical marijuana for children from TIME's Red Border Films_  by [Justin Worland](https://time.com/author/justin-worland/)  ## Justin Worland Senior Correspondent Nov 11, 2014 1:09 PM UTC  Marijuana plants are seen at a indoor cultivation. Marijuana plants are seen at a indoor cultivation.Andres Stapff—Reuters  by [Justin Worland](https://time.com/author/justin-worland/)  ## Justin Worland Senior Correspondent Nov 11, 2014 1:09 PM UTC Repeated marijuana use is correlated with lower IQ scores and less volume in the region of the brain that helps make decisions, according to a new [study.](http://www.pnas.org/content/early/2014/11/05/1415297111.abstract?sid=04b2b519-7a82-4da5-9aa3-1d9da67ee8ef) The study found that the average marijuana user’s IQ was about five points lower than that of a non-user. The earlier the study participants began consuming the drug, the worse the condition of the brain. The study, which compared almost 50 marijuana users to a control group, suggests that at first brains affected by marijuana compensate for the deficit in decision-making brain volume by increasing connectivity, a key brain function. But marijuana-affected brains can’t keep up in the long term. “The results suggest increases in connectivity, both structural and functional that may be compensating for gray matter losses,” said study co-author Sina Aslan, a faculty member at The University of Texas at Dallas. “Eventually, however, the structural connectivity or ‘wiring’ of the brain starts degrading with prolonged marijuana use.” While previous studies have showed that marijuana causes harm to the brains of animals, researchers said they couldn’t be sure whether marijuana use was the cause of the negative changes in the brain. Nonetheless, the study joins a growing [body](http://time.com/3100613/pot-harms-teenage-brain/) of [evidence](http://time.com/2826726/legal-pot-might-make-americas-kids-stupider-say-researchers/) that marijuana harms the brains of young people. 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