Pot smokers might not turn into dopes after all
Revisiting data casts doubts on link between heavy cannabis use and declining IQ.
"Last year, a paper published in Proceedings of the National Academy of Sciences (PNAS)1 suggested that people who used cannabis heavily as teenagerssaw their IQs fall by middle age. But a study published today2 — also in PNAS — says that factors unrelated to cannabis use are to blame for the effect. Nature explores the competing claims."
I would think that there's a link with the socio economic factor.
Maybe they need to do a better controlled study.