Does Weed Lower Your IQ?

Woman smoking medical marijuana joint. Concept of weeds effect on IQ and intelligence

Does weed lower your IQ? This is a question that many cannabis users have wondered about for ages. While temporary short-term memory loss is a common side effect of ingesting the cannabis plant, it has always been of some concern by the public on whether or not cannabis use has any long-term effects on mental acuity and development. The mind is the greatest tool we as humans possess and it is the reason that we dominate the planet and have achieved so much in such a little time. In conjunction, current statistics indicate that about 50% of American citizens have used cannabis in their lifetime. Therefore, it makes tremendous sense, especially with the spread of recreational and medical cannabis use throughout the nation, to look deeper into the question of “Does marijuana affect intelligence?”

The question of whether weed lowers your IQ is especially important because many marijuana users start using marijuana as a teenager.  As a result of legal ramifications and other obstacles, it has been very difficult to truly ascertain the long-term effects that cannabis has on the developing mind. Some studies in the past seemed to show evidence of cannabis use harming the development of the teenage mind as it matures into adulthood. In contrast, other studies seemed to come to the opposing conclusion that marijuana use doesn’t any effect on adolescent brain development at all. Recently, a long-term study attempting to crack the question “Does weed lower your IQ?” was concluded and the data collected seems to be the most complete information that we have ever achieved from such a study.

A ten year long study in California and Minnesota was conducted on 789 pairs of identical teenage twins who either used or abstained from cannabis. It is the first study of this kind that actually looks at the real long-term effects of marijuana use on the adolescent mind. The thing that makes this study radically different than other previous studies on the tie between IQ and cannabis is the fact that this study took a much long-term approach by repeatedly monitoring their subjects rather than only getting information that could only describe a limited window into their lives. As a result of this, a more comprehensive look at the debate of whether or not marijuana affects intelligence was made. Also, many previous studies didn’t isolate the data collected from other variables that could also affect IQ such as dropping out of school, poor living conditions and other environmental factors. However in this study, by using identical twins who have identical genes and living conditions, many of these other variables were nullified so scientists could take a closer look on the effects of marijuana on the developing brain by itself.

So does marijuana affect intelligence?

Image of man rolling medical marijuana. Does weed affect intelligence?

According to this study, it doesn’t seem so! Over the course of the ten-year study, the twins that were using marijuana experienced an IQ level drop of about four points. However, their marijuana abstaining twins also experienced the same drop in IQ over the same period. This suggests that the drop in IQ noticed in the marijuana-using teens was actually not due to marijuana use but instead to some other factor in their lives. As a matter of fact, teenagers that had used cannabis daily for six months or longer showed the same IQ changes to other teenage subjects that had used cannabis fewer than 30 times total in their lives.

However, more research on this matter still needs to be done. While IQ doesn’t seem to be affected by cannabis use, there are other functions in the developing brain that could be potentially affected by cannabis. The fact that there is still very little research on heavy, chronic use of marijuana by teenagers also raises some questions since most previous studies (including this one) only registered how often the teenage subjects used cannabis and not really how much they ingested.

So with this information on the tie between marijuana and the brain, you can enjoy marijuana as you wish without worrying about your IQ. Luckily in Arizona, if you are an adult (and not a teenager!) with a qualifying condition you can legally use cannabis if you desire! If you are wondering how to get a medical cannabis card in AZ go to and come visit us at Affordable Evaluations of Arizona!

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