Scientists Confirm: Cannabis Use Doesn’t Lower Your IQ

Health News - Twin Study

It’s not uncommon to hear people say that using cannabis lowers intelligence; there were even stories of scientific studies that confirmed that belief. However, a recent twin study asks for new interpretations and brings new results.

Back in 2012, a longitudinal study observed people ages 13 to 38 who used cannabis. Scientists interviewed and tested the participants to evaluate their IQ levels and executive functioning, as well as cannabis use patterns. People who started using cannabis during their adolescent years showed a slight decrease in the level of cognitive ability, whereas people who used cannabis in teen years and continued with chronic use experienced the greatest decrease.

This has led researchers to conclude that using cannabis during adolescence had neurotoxic effects on the brain, leading to cognitive decline in early adulthood. Other studies followed the same method and came to the same conclusions, which persuaded the public that chronic cannabis use lowers IQ.

Nevertheless, a most recent study from 2019 questioned the methods of the previous research and found that, despite the strong evidence, cannabis use had no impact whatsoever on a person’s intelligence. On the contrary, the 2019 study discovered that the greatest impact on a person’s IQ level, as well as the likelihood of cannabis use, were genetic and environmental factors.

Even though the 2012 study shows that there is a connection between cannabis use and lower IQ levels, it doesn’t show whether cannabis was, in fact, the one that caused the change in people’s IQ levels (in the first place), or whether it was some other factor.

On the other hand, the 2019 study has used a totally different methodology. The study compared 428 twin pairs for genetic and environmental factors. This twin comparison enabled scientists to observe pairs who had different cannabis usage patterns and see whether they experienced any changes. What’s more, if cannabis really affected the person’s IQ, the twin who used cannabis would have lower cognitive levels, whereas the twin who didn’t use cannabis would have the same IQ, according to the 2012 study.

Instead, the 2019 study only found that in cases where one of the twins was using cannabis, both twins were experiencing IQ drops. Although the 2019 study found some correlation between cannabis use and lower IQ, it also found that genetics, the environment, and other substance use had a far greater impact on a person’s IQ.

Moreover, the study also found that abstaining from cannabis use doesn’t protect people from an intelligence decline.

Plus, studies from 2016 and 2017 have come up with similar results and the same conclusion, which further strengthens the outcome of the 2019 study.

There is still so much left to test, examine, and learn about cannabis use. The study which has been the main argument in the pros and cons debate will soon become obsolete, as it appears that cannabis doesn’t harm anyone’s intelligence.