ā€Ž”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. Despite the fact that the average marijuana user starts at age 17 in the U.S and nearly 7% of high school seniors currently smoke pot every day, IQ scores have risen tremendously over time in all developed countries in recent years. Most of those same countries also experienced a massive increase in marijuana use between the 1950s and today.”–Maia Szalavitz.

 

http://healthland.time.com/2012/08/28/does-weekly-marijuana-use-by-teens-really-cause-a-drop-in-iq/