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Stanford University School of Medicine

The health effects of legalizing marijuana: A Q&A with a Stanford drug policy specialist

MarijuanaRecreational marijuana legalization in California and seven other states leaves quite a few unanswered questions. What are the health risks? Are there benefits? Will children be more likely to use marijuana? What about adults? Will dependence become more common? What does this all mean for legalization at the federal level?

Robert MacCoun, PhD, has many of the answers, which he shared in a recent Stanford Health Policy Q&A. A drug policy specialist, he has studied the legal and health implications of marijuana for years and looks forward to conducting more research on its effects now that legalization is on a roll.

Here's a glimpse:

What are the health risks post-legalization?

That depends on how much consumption levels increase. There are good reasons to expect marijuana prices to fall, which will increase consumption. Because many people use marijuana without health consequences, I worry less about an increase in the number of people using marijuana than about an increase in the number who use it one or more times daily. There is growing evidence that heavy marijuana use is associated with an increased risk of psychosis. We don’t know if it is a true cause-and-effect relationship; let’s hope it is not. But I think the biggest health threat is dependence, which for marijuana is something like getting stuck in the La Brea tar pits — your world just gets smaller and smaller as you get more dysfunctional.


Could there be any positive health effects of marijuana use?

Absolutely. There are plenty of lines of evidence suggesting medical benefits for some patients. Intriguingly, several new studies suggest that medical marijuana states may be experiencing reduced levels of opioid use and opioid overdoses. The Catch 22 is that the DEA decided not to reschedule marijuana because there isn’t enough rigorous evidence, but there isn’t enough rigorous evidence because the Feds have made such studies almost impossible to conduct.

Some of the biggest health benefits of marijuana will occur if it turns out that marijuana use is a substitute for binge drinking. There are both physiological and economic reasons to think that might be the case, but while some studies show substitution, others show complementarity. For a researcher, one big benefit of legalization is that it is going to help us finally answer a lot of these research questions.

Previously: Teens' beliefs about marijuana documented in new Stanford studySaliva test may help identify marijuana-impaired drivers and To keep edibles away from kids, marijuana policies must be "fully baked"
Photo by Bruce Bennett/Getty Images

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