Cannabis Use Not Related To IQ Decline In Teenagers
2 min

Cannabis Use Not Related To IQ Decline In Teenagers

2 min
News Research

New research finds that no, cannabis does not lower the IQ.

Back in 2012, research from the Duke University rallied anti-cannabis campaigners with its findings that heavy marijuana use caused IQ to decline in teenagers. It was quite a controversial finding, and one quickly criticized by other academic institutions for its generalizations and flawed methodology.

Now a new study, conducted by the University College London, one of the most highly regarded academic institutions in the world, found no link between cannabis use and a lowered IQ scores. The research, a longitudinal study, followed the lives of 2,612 children born between 1991 and 1992 up until the age of 15.

Each child’s IQ was tested at the ages of 8 and then again at 15. Each participant was also asked to complete a survey on cannabis use. These results were then analyzed in conjunction with each individual’s academic performance to determine whether cannabis had had any negative impact on their intellectual or academic development. It was found that, once confounding factors were taken into account, there is no evidence that even heavy use of marijuana is associated with a decline in IQ. Confounding factors being alcohol, tobacco and other drug use, as well as things like maternal education.

Quite interestingly, but not unsurprisingly, it is alcohol use that was found to be strongly associated with a decline in IQ.

However, the study did find that students who were heavy users of marijuana performed slightly worse in exams, scoring roughly 3% lower than those who were not heavy users.

A Correlation, Not A Cause

An accompanying statement from the lead author noted that, "this is a potentially important public health message - the belief that cannabis is particularly harmful may detract focus from and awareness of other potentially harmful behaviors." This is a very powerful statement. The main argument of anti-cannabis campaigners is that cannabis harms, but this evidence would suggest that by focusing on cannabis, we are ignoring other lifestyle choices that may be causing harm; and that cannabis use can be a correlation, not a cause.

A Prime Example

A great example of just what not to do comes from our favorite scaremongers, The Daily Mail. The Daily Mail has also reported on the findings of this study, but instead of giving the full story, and spreading the message of these finding, they have cherry picked information and latched onto the outcome that heavy cannabis users score up to 3% less on exams than non-heavy users and those who don’t use at all – we would like to particular emphasize the point that this doesn’t include most normal cannabis users, only the heaviest. It is a prime example of how anti-cannabis establishments are grabbing the wrong end of the stick, and failing to take the bigger picture into account.

Of course we do not advocate the irresponsible underage use of drugs. But teenagers DO use cannabis, and by focusing on the cannabis use when it has been shown not to effect intelligence, instead of other things like alcohol use, is very misguided. And if anti-cannabis campaigners are really worried about the effects of cannabis on children, then surely cannabis should be legalized and controlled, making it so that only people over 18 or 21 can obtain it, instead of anyone with a €20 note.

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