Cannabis & adolescents, IQ unchanged

Cannabis & adolescents, IQ unchanged

Studies confirm that marijuana does not lower teens IQ

We are all familiar with the stereotypes and prejudices that encompass adolescent cannabis use, which has not discouraged researchers who have attempted to trace the link between cannabis use and intelligence for decades. … One of the longest studies ever mStudies on the subject finally confirmed that cannabis does not lower the “adolescent” IQ.


In October 2012, researchers published a major study spanning thirty years. The study claims that cannabis use lowers the “intelligence quotient” or IQ of the cannabis user. According to the study, these effects were worse if the subject was a very regular cannabis user… And unfortunately this is not the only study that claimed that marijuana causes a decline in neuropsychological capacity or cognitive in cannabis users.

But four years later, researchers published a study that challenged the 2012 research. Two studies compared two groups of teens. A group of adolescents who used cannabis and other control group who abstained from smoking or using marijuana. The researchers carried out the first study at the universities of London and Bristol. Their findings confirm thatthere is no measurable link between cannabis use and low IQ in young people.


The details of the study paint a more realistic picture as 2235 adolescents were in the study. Those who used cannabis more than 50x in a year showed the same IQ and academic performance as their peers who abstained from smoking. Even if the study is very clear, today the debate remains lively. Particularly on how cannabis affects cognitive functions associated with learning and memory.

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Factors that influence intelligence

But this study deserves to be considered because it was able to take into account other important factors that influence intelligence: Smoking cigarettes, turns out to be one of the factors that can decrease adolescent IQ. As well as depression, stress and the environment. But researchers say moderate cannabis use may have a smaller impact on cognition than other studies suggest.

adolescents, IQ, IQ cannabis
The study did not include adolescents who use cannabis very heavily (heavily dosed) or very regularly ...

The study of twins

American researchers conducted a second study. This study is fascinating because it was made on twins. Over a 10-year period, the study looked at the effects of marijuana on 2 teenage twins. In each group of twins, one twin was a regular cannabis user, and the other was not. The results are complex, but give a clearer picture of the relationship between cannabis and IQ.


The study indicated that yes, marijuana users had lower IQ test scores than their counterparts. Additionally, adolescent cannabis users have shown a significant decline in "crystallized intelligence" between early and late adolescence.


“Crystallized intelligence is the ability to use skills, knowledge and experience. It does not correspond to memory, but relies on access to information in long-term memory. »Wikipedia

Even though the study seems to suggest that marijuana makes you stupid, researchers couldn't find any supporting evidence. It turns out that the decline in IQ is more likely related to family and emotional factors.


The study claims family and emotional issues are linked to the initiation of marijuana. Including the way we perceive the act of smoking in the first place, and not to its direct consumption. However, the use of cannabis itself has not caused a drop in IQ but it does happen every time other factors were involved...

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