Why cannabis’s health effects are so hard to study
episodePreviously titled “Where are we with understanding the health effects of cannabis?” — renamed by the publisher on Sep 11, 2026
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Why has cannabis use surged from 25 million to 70 million Americans?
Hey it's Flora and you're listening to Science Friday. When states first began legalizing recreational cannabis a couple decades ago, 25 million Americans said they used the drug, according to the National Survey on Drug Use and Health. That number nearly tripled to 70 million in 2023. And there are a lot of open questions. Why do some people find more pain relief from THC than traditional painkillers? Does it really help your sleep? What are the effects of long term use? We have two scientists here with us who are on the forefront of that research. Dr. Ryan Vandray is an experimental psychologist at the Johns Hopkins Cannabis Science Laboratory. He's studied the health effects of cannabis for 26 years, and Dr.
Natasha Wade, a neuropsychologist who studies the effects of substance abuse on adolescent brains. She recently analyzed data from Eleven thousand teens about how cannabis is affecting their development. Welcome to you both to Science Friday.
Thanks for having us, Flora. Thanks
for having us. Thank you both for being here. Ryan, you've said that the cannabis market has been allowed to run rampant. Tell me more about that and and sort of what it means for you studying it.
Yeah, so um, you know, when I started we were just looking about uh yeah, cannabis is a drug of abuse and um yeah, people were smoking flour and that was it, right? And so the kinds of questions that we're concerned with now have changed dramatically because now we have medical markets, we have adult use markets, and we have hundreds of different products. Um and so we have to understand Um, what kinds of products are potentially helpful or harmful for the medical application for dozens of different health conditions? We need to understand how the route of administration, the formulation, and the dose affect different people. And we have to, you know, kind of go back to our is it a drug of abuse kind of questions and and revisit that in this novel marketplace.
So we're trying to look at this from a lot of different perspectives.
How does the exploding variety of cannabis products complicate research?
And, you know, there's been very few guardrails put up with regards to what kinds of cannabis products the industry can put out and the claims they can make about it. So as scientists, we're kind of constantly playing catch up. to this to try to understand, okay, well, there's this new kind of product. What does that mean? How does it compare to the more traditional forms of of cannabis that we uh tend to come across?
Yeah, that's interesting. I mean, it sounds like it's different than alcohol, right? Because there are actually different compounds. So it sounds like a lot more variables than other drugs.
It's different compounds and it's different ways in which it's being used and purposes for which it's being used, right? And so alcohol is a fairly standard beverage. You drink it and there's you know, a couple different variants there. You've got kind of beer and wine and then you have spirits. With cannabis, you've got oral dosing, you've got uh inhaled dosing with different kinds of devices, you have topicals, you have suppositories. And so many diff uh each one of those variants changes the experience of the user and then you throw on top of that uh a whole range of of chemical entities, you know alcohol is a single molecule. In cannabis you've got THC and C B D and C B N and C B G and a whole alphabet soup of different kinds of chemicals that make up these products.
Tasha, you study teens. Are teens using cannabis differently than they used to?
Uh, absolutely. I think that with all these different products, like Ryan was just saying, there's there's a lot more accessible to them. We're seeing that there's a lot more co-use of cannabis, especially with nicotine products, which also might even change the experience and the downstream effects of use and perhaps will make it worse, perhaps might mitigate some of the effects. Uh, but the jury's still out, we still have a lot more to do to actually figure it out because Because everything is changing so rapidly right now.
Well, tell me about this recent study where you looked at neurological development in teens who use cannabis.
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Chapters
8 chapters
1
Why has cannabis use surged from 25 million to 70 million Americans?
0:02–2:06
2
How does the exploding variety of cannabis products complicate research?
2:06–4:12
3
What does the teen‑development study reveal about cannabis and cognition?
4:12–6:48
4
Which medical conditions show the most promise for cannabinoid therapy?
6:48–9:16
5
How do dose, formulation, and route of administration affect therapeutic outcomes?
9:16–11:47
6
Will federal rescheduling make cannabis research easier?
11:47–14:46
7
How do dispensaries and bud‑tenders influence consumer safety and information?
14:46–16:31
8
What advice should teens and new users follow when considering cannabis?
16:31–18:18
Speakers
1 identifiedMore from Science Friday
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