Does weekly marijuana use by teens really cause a drop in IQ?

A new study suggests marijuana use could have an impact on America's IQ, but how great is the effect?
28 August 2012
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Heavy marijuana use is associated with cognitive decline in about 5% of teens, according to a new study, which suggests that the heaviest users could lose 8 IQ points, according to a report, published in the Proceedings of the National Academy of Sciences. If the link is real, the effects on cognition could be dramatic. But intelligence and cognition is affected by a plethora of other factors, including genetic, social and environmental influences that may supersede any influence from drug use. 

Tuesday, August 28, 2012
Time Magazine (US)