Does Cannabis Really Shrink Your Brain? Let’s Clear the Haze!

A Deep Dive into Cannabis and How it Affects Your Brain

Welcome to your personalized journey into the world of cannabis and cognition! Today, I’m unpacking some seriously interesting studies on how cannabis use might impact your brain, cognitive abilities, and even your driving skills. If you're looking to go beyond the “cannabis is good or bad” debate, you’re in the right place. Let’s break it down with a mix of research, humor, and a splash of common sense.

For anyone who wants to pour through the published literature supporting these take aways, here’s a Google Drive folder of 8 studies

Ready? Let’s dive in!

Cannabis and Subjective Cognitive Decline: What’s That?

One of the studies we explored looked at the concept of “subjective cognitive decline.” In short, this refers to whether people feel like their thinking skills have taken a hit. Using data from over half a million U.S. adults, the study found that cannabis users—whether for medical or recreational reasons—were more likely to say their cognitive abilities weren’t as sharp. But does that mean cannabis is to blame? Not so fast. The research doesn't prove cause and effect, and it’s just as likely that lifestyle choices or even societal stigma could be factors.

Brain Shrinkage: A Scary Myth?

Another study looked into whether cannabis actually shrinks your brain (cue scary music!). Using brain scans on a small group of people living with HIV, the researchers found that those who used more cannabis had slightly smaller brain volumes in certain areas. But here’s the plot twist: these differences were there before the study started! In other words, it’s likely that pre-existing brain differences could influence why some people use cannabis more than others, rather than cannabis shrinking brains. Phew, right?

Driving with Cannabis: Pedestrians Beware?

We also dove into a driving simulator study from 2020 that tested cannabis users’ skills behind the wheel. The result? Cannabis users who hadn’t consumed in over 12 hours still performed worse than non-users—more missed stop signs, more simulated pedestrian mishaps (yikes!). But here’s where it gets interesting: impulsivity played a major role. Once the researchers accounted for impulsive behavior, the gap between users and non-users nearly vanished. It turns out, it’s not that cannabis turns you into a reckless driver, but if you’re already impulsive, cannabis might amplify that.

Takeaways:

• Cannabis and Cognitive Decline: Cannabis users report feeling less sharp, but we can’t be sure cannabis is the cause.

• Brain Shrinkage? Not So Fast: Brain volume differences were pre-existing in cannabis users, suggesting the effects are more complicated than cannabis = brain shrinkage.

• Driving Skills: Cannabis can impair driving skills, especially in impulsive individuals, even when sober.

• Medical Cannabis and Executive Function: One pilot study suggested medical cannabis might actually improve executive function after a few months of use, but more research is needed.

Why This Matters