My Brain on Cannabis

When it comes to intelligence, cannabis has had a bad reputation. We’ve all seen the media representations of ‘stoners’ as bumbling, forgetful, and unfocused characters, and maybe we’ve even had some experiences ourselves where we’ve felt stupefied by some potent bud. Difficulty with short term memory recall and slowed cognitive functioning are commonly reported side effects of cannabis use. So, you might worry that an increasingly cannabis using nation is likely to get a lot less intelligent as well.

I had this worry myself before I started using cannabis. I decided to start using it as a regular daily medicine while I was in the middle of the most intellectually challenging period of my life – the end of my doctorate program. I was writing a dissertation on the philosophy of science- a field that requires mastering both the theoretical intricacies of philosophy and the rigorous methodology of science. My lengthy research project would all culminate in a verbal defense where I would be questioned by a panel of 5 professors from multiple academic departments. I needed to be at my best. But my chronic pain and anxiety conditions – which I had been managing with prescription medications- started to resurface and intensify.

Some of the symptoms of my condition were painful like the extreme muscle tension, constant nausea, headaches and sense of generalized pain. But I was most troubled by the cognitive effects. Most days, I couldn’t focus or think clearly. I was having a hard time remembering information and my energy was so low it was difficult to get anything done. The conventional medications which had worked for the last few years had started to cause rebound symptoms and the doctors told me it was only likely to get worse until I went off of them completely. They had no more suggestions. And so I turned to cannabis; fearing greatly that it would stunt the intellectual abilities that had brought me to graduate school.

I expected some cognitive challenges to accompany daily cannabis use, and at first, they did. I felt totally useless during the first few days, but that wasn’t a change. I was already experiencing cognitive difficulties from my painful condition. With cannabis I felt completely free from pain, if a little silly and sleepy. Still, after only a few days of smoking cannabis during the day, I found that I was starting to think quite clearly. I didn’t feel “stoned” anymore. Without the crippling pain and muscle tension, my mind came back to life. Far from crippling my natural intelligence, the cannabis allowed for it. And for the first time in months, I could think. As surprised as I was, the research actually predicts this. Studies of heavy chronic cannabis users show that they don’t experience the same cognitive changes that we see in occasional users.

I also noticed that certain strains worked better for me than others, and indeed research is also now finding that certain cannabinoids and terpenes (present in higher quantities in some strains) can counter the cognitive changes associated with THC intake, even for occasional users. In other words, some cannabis might make you feel a little slow, but not all will.

Soon I was back at work, and off of sick leave. I smoked cannabis right before my successful dissertation defense. And despite my time on sick leave, I finished my program in less time than most of my healthy, non-cannabis using classmates. For me, cannabis only helped my academic achievement, and I wasn’t the only academic I knew with this story. I had friends with ADHD who used it to focus, some who used it to deal with persistent back pain, others who used it to manage the effects of  PTSD. All were brilliant and academically accomplished. This left me puzzled by the recurrent warnings from scientists that cannabis use would diminish your intellectual abilities. So I decided to delve into the research to find out the real story.

One of the most commonly cited justifications for these warnings is the research suggesting that cannabis use in children and adolescents could lead to permanent IQ loss. The science seemed to back this claim up, with longitudinal studies, like this one from 2012, showing an average drop of 4 IQ points in teens who used cannabis.

But more recent studies are calling these theories into question, and taking a second look at the research that convinced us in the first place. In their 2016 study, co-authors Jackson and Isen took a unique approach to the issue by studying cannabis use and IQ in twins. By looking at twin pairs, where one twin used cannabis as a teen, and the other did not, they were able to see whether cannabis use, or other factors, were at play. While the IQ drop was still seen in cannabis using teens, they found that cannabis use did not correlate with IQ differences in twin pairs. The cannabis using twin experienced an IQ decline, but so did the non-cannabis user. As Jackson explains, “while we do see an association of adolescent marijuana use with IQ decline, we believe this association is due to something else that makes it likely for someone to have both a low IQ and also be a marijuana user. Our findings lead us to believe that this “something else” is related to dysfunction in the child’s environment, whether that be their home, school or peer environment.” This doesn’t mean that cannabis only appeals to less intelligent people. It means that when people are in other challenging situations, it can affect their intellectual abilities – and give them reasons to seek comfort in cannabis.

So if something else is responsible for both lowered IQ and an increased likelihood to use cannabis, what might this “something else” be? According to the research, there are multiple possibilities. Some researchers suggests the cannabis/IQ association can be explained by differences in socioeconomic situations. The worse off your socioeconomic situation the more likely you are to be exposed to cannabis at a young age and research also shows that lower socioeconomic status is correlated with lower IQ.  

Another 2016 study suggested that cigarette smoking could be a confounding factor, showing that the association between cannabis and IQ loss disappears when tobacco use is taken into consideration. When we look at those teens who use cannabis alone, and refrain from tobacco use, we don’t see the IQ drop. This suggests that tobacco use is the more likely culprit for the diminished intelligence.

A third possibility, which is mostly absent from the current literature, is the presence of pain. A recent study showed that adolescents who report being in pain also have poorer grades and reduced ability to focus. Pain relief is also the top cited reason for using cannabis, accounting for up to 97% of cannabis users. Given the pain relieving properties of cannabis, teens suffering from chronic pain conditions may be both more likely to use cannabis and more likely to have a lower IQ.  

Our understanding of cannabis and its effects on the brain will only improve as our research does, but the most current research does not suggest cannabis use will permanently harm your intelligence. If you pick the right strain, it might not even affect it temporarily. Research even suggests cannabis can protect your intelligence and memory as you age, or after a concussion. It may take a while to change cannabis’ image. But despite its bad reputation, cannabis use may be a lot smarter than we originally thought.