New Study on Marijuana Use & IQ Could Surprise You

weedNot many parents would be particularly thrilled to discover that their kid is smoking pot, but if this does happen to you, it turns out there's at least one thing you probably don't have to worry about: A new study shows that marijuana use in teens may not in fact lead to a decline in intelligence.


While the results of past studies prompted researchers to suggest that adolescents were particularly vulnerable to potential harm from smoking weed, this latest study (released Monday by the Proceedings of the National Academy of Sciences) challenged the idea. 

Drug use in kids is a tricky thing to research, since obviously children can't ethically be chosen to take recreational drugs in the name of science. So for this study, the researchers analyzed data previously collected for two large US studies of twins. Upon examining the trajectories of teen test scores and comparing whether those trajectories were worse for marijuana users than non-marijuana users, the study authors found that there was no difference between the two groups on most tests (though kids who used did not do as well on tests of vocabulary and general knowledge).

But what about kids who smoked, like, a LOT of pot versus those who just dabbled? The researchers found no difference at all there, even with kids who used daily and/or had smoked over 30 times. 

More from CafeMom: Dad Who Gives His 6-Year-Old Son Marijuana Did What Any Parent Would (VIDEO)

Perhaps the most interesting part of this study is what researchers found when they compared 290 pairs of twins in which one twin had smoked pot and the other had abstained. (All sets of twins had grown up together; 137 pairs were identical twins, meaning they shared the same DNA.) In these cases, too, the pot users did not do any worse than their non-using siblings.

Food for thought (and probably a relief to many). Then again, what about the previous research? Was it completely invalid? Study author Joshua Isen, a lecturer in psychology at Loyola Marymount University in Los Angeles, theorizes that a child at risk for becoming a marijuana user "is probably going to show this IQ drop regardless of whether he or she is actually smoking marijuana," which makes a lot of sense. And Isen also points out that this study did not look at any other potentially harmful effects of smoking pot in adolescence. More research clearly needs to be done, and indeed it will be: The government has reportedly begun a project which will follow approximately 10,000 children over a period of time to assess the impact of marijuana (and other drug) use. In the meantime, of course, there are a million other reasons why parents will continue to hope that their child doesn't start smoking pot, or using any other substance. But at least compromised intelligence won't be one of them!


Image via Katheirne Hitt/Flickr

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