Does Marijuana Lower Your IQ? Not According to These Studies

It’s one of the most obsequious stereotypes in all of pop culture. The stoned out dude (it’s almost always a dude) acting like a moron.

For reference, here’s Jeff Spicoli beating his head with a shoe back in 1982’s “Fast Times at Ridgemont High.”

But is that the true nature of marijuana smokers? Of course not. That is very last century. And also a comedy looking for laughs.

Marijuana and Your IQ

In real life, marijuana is now accepted and used by people in all walks of life. Scientist Carl Sagan and Apple founder Steve Jobs, for example, both admitted to marijuana use and they did pretty well for themselves.

The same goes for many artists, writers and musicians. As Justin Timberlake once said of using marijuana, “Sometimes I have a brain that just needs to be turned off.”

He meant that as a way to relax, like a person might enjoy a glass of wine or a bottle of craft beer. But even that quote can be interpreted to mean using marijuana equals making yourself stupid.

In the early part of this decade, that also was the finding of a scientific study conducted in New Zealand. That study claimed to find chronic marijuana use among teens led to a permanent drop in IQ points.

Teen use of marijuana is certainly a no-no. However, research since the New Zealand study has shown that there may not be a correlation between marijuana use and declining IQ.

More Recent Studies

A Cornell University study, published in 2016, found no relationship between marijuana use and lowered IQ.

Acknowledging the scarcity of research on the topic – as well as the conflicting opinions of many people – researchers decided to study twins. One twin had self-reported use of marijuana, the other had abstained. They were given intelligence tests at 9 to 12 years old (before any marijuana use) and again between the ages of 17 and 20.

The results? Researchers reported that “marijuana-using twins failed to show significantly greater IQ decline relative to their abstinent siblings.”

A study in the United Kingdom, published in early 2016, drew the same conclusion. They found cigarette smoking has more correlation with declining IQ scores than marijuana use.

More on New Zealand Study

Even the New Zealand research on teen use of marijuana was called into question by the very same periodical that first published the study.

Having published the study in 2012, the Proceedings of the National Academy of Sciences of the United States of America returned in early 2013 with a follow up that called the study “flawed and the causal inference drawn from the results premature,” according to Paste.

The main argument was the study ignored other factors, such as environment, educational level and socioeconomic status.

This was backed up by Psychology Today, which reviewed the research and looked at the details of how people in the study were tested. They found that verbal IQ scores had dropped. However, other scores – arithmetic, block design and picture completion – had not.

They called the report’s findings “premature and most likely overestimated.”

Bottom line, the scientific jury is still out. But certainly the most recent studies have shown that marijuana doesn’t turn you into Jeff Spicoli.

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