Recently the question has resurfaced: does cannabis use lower your IQ? With the pending legalization of recreational cannabis all over Canada, and in some places of the U.S, there’s growing concern about what effect cannabis will have on the IQ of the public, especially that of younger individuals.
This question has been debated for a long time, and there’s evidence on both sides. Many people are staunchly against cannabis use, sighting its ability to “make you dumb”, while others on the opposite side note its ability to increase focus. Some people say cannabis use is fine for adults but not adolescents. So who should we believe?
The Seminal Dunedin Study
Perhaps the most famous and widely cited study conducted on the effects of cannabis use on cognition is the seminal Dunedin Study headed by Madeline Meier. The study consisted of 1,037 individuals born in 1972 or 1973. The subjects, who all consistently used cannabis for the duration of the study, were monitored for 38 years starting around age 12 or 13. The study found decline across cognitive function in those who began cannabis use in adolescence, especially in those who were heavy users.
Their findings are disheartening, but the study failed to consider some important factors such as income level, education access, and childhood adversity. There could also be other underlying cognitive factors that could increase the risk of decline in IQ, and those may coincide with the tendency for cannabis dependence. Still, the Dunedin Study is one of the most prominently cited studies.
The Twin Study
Another study, released in 2016, had a more positive outcome. Scientists followed 789 pairs of twins and surveyed them throughout their development about their cannabis use, drug use, alcohol consumption, and other factors that could affect IQ. From age 9 to age 20 participants were monitored and it was found that there was no difference in the cognitive function of a twin that consumed cannabis, and the other who did not. These findings have left many hopeful, but can’t yet be taken as complete truth without further study.
There have been other ongoing studies that have found no decline in the IQ of those who use cannabis early in life. One study from Britain of 2235 teenagers from the Avon Longitudinal Study of Parents and Children found no difference over time in the subjects who used cannabis than those who abstained. The evidence, just like in the twin study, needs more support before we can really say that cannabis doesn’t have an adverse effect on young minds, but it does lend some hope that cannabis doesn’t lower IQ.
So What’s the Deal?
For now, we don’t know the effect that cannabis use has on adolescent minds. Hopefully, with the pending legalization of cannabis in Canada and in many States across the U.S it will be studied much more, and better understood. Until then, it will be the underage peoples choice to light up or not but, be sure to keep your eyes out for the scientific studies that are sure to come.
Shasta Nelson is a California Native and a cannabis connoisseur. She's been involved in the industry at every level since she was a teenager. Currently she provides content for Roottie, DOPE Magazine, and Terpenes and Testing. She's also a creative writer, with a graphic novel underway.