New Marijuana Risks Revealed

Negative effects on the mind and body are emerging through a haze of rampant speculation, good anecdotal vibes and sheer hope

Few recreational drugs seem to generate as much conjecture, confusion and controversy, over so many decades, as marijuana. Some see it as a remedy for just about every ailment under the sun. Others deem it the devil’s weed, a gateway to heavier drug use. Lots of folks in the middle just wanna have fun.

To be clear, there are significant medical applications for marijuana, though in many cases the safety and effectiveness have yet to be fully determined through long-term, clinical research. For recreational users, moderation can matter, as with any drug.

But this story isn’t about that. As a science writer and occasional partaker, I’m compelled to take an honest look at potential risks related to what is, after all, a phenomenally powerful mind-altering drug. Whether you need it, merely enjoy it, or aim to influence someone else who does, there’s no harm in knowing what can go wrong, I figure.

Your brain on pot: THC is known to impair “only” the areas noted with yellow dots. Graphic: NIDA

One big caveat: We lack firm conclusions on a lot of this.

Because marijuana is classified as a Schedule I drug in the US, research into it is notably limited. Much of the existing analysis is observational, relying on surveys and self-reporting rather than the rigor of randomized, controlled clinical trials. The shortcomings have only become more significant in recent years with the increased potency of pot.

“A lot of our views about cannabis, unfortunately, are not driven by good science, but driven more by opinion,” says Joao De Aquino, MD, assistant professor of psychiatry at the Yale University School of Medicine.

But scientists know a lot about the mental effects of pot, which we’ll get to below. And as of this week, they know a bit more about the physical effects.

Heart health problems

A new study, published Feb. 28 in the Journal of the American Heart Association, finds that daily marijuana smoking (the primary means of ingestion analyzed by the researchers) is linked to a 25% higher risk of heart attack and a 42% greater risk of stroke, compared to people…