IQ and cannabis – is there any connection?

You’ve probably heard a lot of information about how cannabis kills brain cells and makes people dumber. There has even been research done on this to clarify and confirm this myth. However, a new study has come to light that overshadows the original one with new arguments. What are they?

Earlier research pointing to a reduction in IQ due to cannabis use

The idea that cannabis limits and reduces our cognitive function is not exactly a figment of human imagination. This idea has been floating around society for many years and has become a sort of propaganda tool against cannabis use.  It was only in 2012 that a study came to light linking marijuana use and rapid cognitive decline and IQ in teenagers.

The study itself focused on people aged 13-38. Participants filled out general information about themselves, took traditional IQ tests and indicated whether they had experience with marijuana.

You may already be guessing where this scientific analysis was going. Participants with marijuana experience scored worse on these tests. Those who had used cannabis in larger quantities even had a noted drop in IQ scores.

From this study, the researchers concluded that cannabis must somehow intoxicate the brain, leading to certain disorders, especially during the years of adolescence. Other studies, mostly identical or with minimal differences, began to follow this study.

And then what happened? From every corner you could hear that if people smoked weed they would be stupid, unsuccessful and other such nonsense.

But in the end it turned out that certain aspects of the issue were perceived a little differently.

IQ and cannabis – a twin study and research from 2012

This may seem like compelling evidence leading to cognitive decline, but a 2019 study calls into question the methodology that led to the 2012 results. Thus, the new study suggests that conclusions regarding cannabis and reduced IQ may have been premature.

A study on twins suggests that marijuana is not behind any psychological disorders at all. Instead, researchers have come up with the theory that it is more likely that genetic and environmental factors lead to lowered IQ and predisposition to cannabis use.

So how is it possible that two similar studies can differ in such a fundamental way? It is probably a different approach to the issue and a different point of view.

The 2012 study very clearly describes the link between cannabis use and a reduction in the intelligence quotient. But it no longer shows whether marijuana is really behind the reduced IQ. It raises the possibility that something other than cannabis is behind the reduced intelligence. Socio-economic status or tobacco use are good examples. That too can degenerate our brains.

How does a 2019 study address this issue?

“The study conducted on twins is specifically designed to research the underlying relationships. Identical twins have a completely identical gene code and are exposed to identical influences. If we focus on those genetic and environmental factors, we can compare them between pairs of twins,” says Dr Jessica Megan Ross, author and leader of the paper.

Abstinence won’t protect your IQ

Dr. Ross’ study, like the 2012 paper, focused on cognition and IQ research, but instead of individuals, 428 pairs of twins were invited. By tracking the twins, who differed mainly in their cannabis consumption, Dr Ross and her team were able to see if there were any changes in each pair.

If cannabis does indeed intoxicate the brain (as the 2012 study suggests), then logically one twin would have a drop in IQ, compared to their counterpart. But that didn’t happen. In the case where one twin used marijuana, they saw a drop in IQ in both twins.

“Our study thus refutes the results of previous work that cannabis is responsible for poorer cognitive function. We found a conclusive link between cannabis use and cognitive decline, but cannabis itself is not the cause. Otherwise, the abstinent twin would still have the same cognitive function compared to its counterpart”.

Dr Ross therefore argues that cannabis has nothing to do with a reduction in the intelligence quotient. Genetic and environmental factors play a bigger role, she says.

Previous studies have had similar results

However, last year’s research is not the first to look at this issue. Twin studies of similar vintage were conducted in 2004, 2016 and 2017. The results were almost identical.

The 2019 work greatly strengthened the results of the previous work. Among other things, it also addressed the topic of overall musculoskeletal functioning, muscle memory and the effect of cannabis on these functions. The data collection and work with the twins was more intensive and focused mainly on the period of adolescence and the effects of cannabis at that time.

Unfortunately, these studies had one flaw. None of the participants were truly heavy cannabis users. Most of the couples could be described as occasional users. None were labeled as “heavy smokers” who used cannabis perhaps several times a day.

Dr. Ross herself uttered a popular phrase in scientific circles. This was again about the need for more understanding of the pros and cons of cannabis use and that research is still evolving.

In any case, we can say with peace of mind that cannabis does not make you stupid. If you meet anyone who says otherwise, you can refer them to Dr Ross’s study.

If you are curious if cannabis really affects the human mind, try some of our cannabis seeds and the plant that grows from them will satisfy your curiosity.

Do you agree with the claim that smoking/using marijuana has a negative effect on IQ? Or do you lean towards genetic and environmental factors that can impair our cognitive function?