http://www.universityprimetime.com/marijuana-increases-your-iq-according-to-new-study/ you are welcome. There has been a lot of other researches about marijuana and iq and all of the have had similar results.
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`"A
report coming from Harvard University found that long-term smoking has absolutely no negative impact on intelligence. The study of cognitive changes caused by heavy marijuana use has found no lasting effects 28 days after quitting. Following a month of abstinence, men and women who smoked pot at least 5,000 times in their lives performed just as well on psychological tests as people who used pot sparingly or not at all, according to a report in the latest edition of the Archives of General Psychiatry.
In all of these studies, there is absolutely NO evidence that moderate marijuana smoking causes any decrease in cognitive functionings and IQ levels. In fact, their results indicate the exact opposite if you use it in moderation."