Where are we with understanding the health effects of cannabis?

September 11, 2026

AI Summary

5 min read

When states first began legalizing recreational cannabis, about 25 million Americans reported using the drug. That number has since nearly tripled to 70 million, yet the science of what cannabis actually does to the body and brain has struggled to keep pace. Researchers Ryan Van Dray and Natasha Wade joined Science Friday to explain where the evidence stands—and why the current marketplace has made their jobs vastly more complicated.

The cannabis market has outpaced the science

Van Dray, an experimental psychologist at the Johns Hopkins Cannabis Science Laboratory who has studied cannabis for 26 years, describes the current situation as one where the market has been allowed to "run rampant." When he started, people mostly smoked flower, and the central question was whether cannabis was a drug of abuse. Today, there are hundreds of products—edibles, vapes, tinctures, topicals, suppositories—each with different chemical profiles. "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," Van Dray said. "As scientists, we're kind of constantly playing catch-up."

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What you'll learn

1 (01:18) **Cannabis Use Has Tripled, Research Is Playing Catch-Up** - Host Flora Lichtman frames the episode: 25 million users two decades ago vs. 70 million today, introducing two scientists to discuss the open questions about health effects.
2 (02:18) **The "Rampant" Market: More Variables Than Alcohol** - Dr. Van Dray describes how cannabis research is far more complex than alcohol research.
3 (04:42) **Teen Cannabis Use and Cognitive Development** - Dr. Wade presents top-line findings from a study tracking 11,000 adolescents over nearly a decade.
4 (06:29) **Defining "Cognitive Gains" in Teens** - Dr. Wade clarifies what the study measured.
5 (06:58) **Cannabis as a Therapeutic: Proven and Promising Conditions** - Dr. Van Dray outlines the medical applications.
6 (08:15) **Dose: Therapeutic Benefits Without the High** - Dr. Van Dray discusses how little THC may be needed for medical effect.
7 (10:10) **Rescheduling Cannabis: What It Would Mean for Research** - Dr. Van Dray explains the practical impact of moving cannabis from Schedule I to Schedule III.

+ Full timestamped outline available in the app

Show Notes

When states began legalizing recreational cannabis a couple decades ago, 25 million Americans said they used the drug. That number nearly tripled to 70 million by 2023.

There are a lot of open questions about how it affects us. Why do some people find more pain relief from THC than traditional painkillers? Is it really better for sleep? What are the effects of long-term use?

Host Flora Lichtman is joined by two scientists taking on these kinds of questions: Experimental psychologist Ryan Vandrey, who’s studied the health effects of cannabis for 26 years, and neuropsychologist Natasha Wade, who studies the effects of substance abuse on adolescent brains. She recently analyzed data from 11,000 teens to understand how cannabis affects development.

Guests:

Dr. Ryan Vandrey is an experimental psychologist and professor at the Johns Hopkins University Behavioral Pharmacology Research Unit and helps lead the Johns Hopkins Cannabis Science Lab.

Dr. Natasha Wade is an associate professor in the Department of Psychiatry at UC San Diego and licensed clinical neuropsychologist.

Transcript will be available after the show airs on sciencefriday.com.

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