Episode 68: Cannabis

Episode 68: Cannabis

Author: Tom Chivers and Stuart Ritchie April 1, 2025 Duration: 1:02:47

The Studies Show LIVE! Get your tickets for our live show in London on Friday 9 May at this link.

Blaze it up! It’s time for an episode on cannabis. And just to be clear, not “on cannabis”, but “on, as in about, cannabis”. What’s the evidence that this incredibly popular drug will lower your IQ? What about the question of whether it causes psychosis?

In this toked-up episode of The Studies Show, Tom and Stuart try to find out—and gracefully refrain from any “drug humour” while doing so.

The Studies Show is brought to you by Works in Progress magazine. Why does all that steam come out of the ground in New York City? Why are pineapples the greatest fruit? What on Earth was the Hanseatic League? All of these questions and more are answered in their most recent issue, available 100% free at www.worksinprogress.co.

Show notes

* A summary of the endocannabinoid system

* 2015 review of the evidence on the psychological effects of cannabis

* Famous 1987 study of Swedish soldiers on cannabis and psychosis

* The NEMESIS study

* 2007 systematic review of longitudinal studies of cannabis and psychosis

* 2022 systematic review and meta-analysis with results on dose-response

* Study finding earlier use predicts higher psychosis risk

* 2023 study on sex differences in the cannabis-psychosis relation

* Example of a Mendelian Randomisation study on cannabis and psychosis

* Data on cannabis exposure over time in the UK

* Dunedin Cohort study on cannabis and IQ

* And a response to some controversy over the data

* 2021 systematic review of IQ decline after smoking cannabis

Credits

The Studies Show is produced by Julian Mayers at Yada Yada Productions.



This is a public episode. If you'd like to discuss this with other subscribers or get access to bonus episodes, visit sciencefictionspod.substack.com/subscribe

Every week, Tom Chivers and Stuart Ritchie pull apart the biggest arguments and most confusing claims making headlines. Science Fictions isn't just about celebrating breakthroughs; it's a necessary dive into the messy, contested, and often surprising realities of how science actually works. You'll hear them unpack heated debates, examine questionable studies, and explore why even solid research can sometimes lead to public confusion. This podcast serves as a guide through the noise, separating compelling evidence from overblown narratives. Each episode feels like a conversation with two deeply informed friends who aren't afraid to ask tough questions, offering clarity on topics that matter. For anyone curious about the stories behind the science headlines, this is an essential listen. Tune in for thoughtful analysis that goes beyond the press release, grounded in a genuine fascination with how we know what we know.
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