When it comes to polarizing health topics, few subjects spark more debate than weed (except maybe CrossFit or the Paleo Diet). Can it improve your health? Lower stress? Make you more forgetful? Even make you skinnier?
The science is still, well, hazy—but some research is starting to give us an idea of what exactly weed does to the human body.
For instance: Toking up regularly could dull your emotional response and cause addiction, according to a marijuana study from the University of Michigan Health System. Researchers analyzed 108 people in their early 20s (69 men and 39 women), all of whom were taking part in a larger study of substance use. In the study, participants sat in an MRI while they played a game, in which they pressed a button when they saw a target on a computer screen cross in front of them. Before each round, they were told they could win 20 cents or $5—or they might lose that amount, or have no reward or loss. Scientists assessed the moment of anticipation (a.k.a. when volunteers knew they could get a few dollars richer).
Now, you’d think getting free money would be cause for excitement, but scientists found the more marijuana use volunteers reported, the less their reward centers were activated.
“Over time, marijuana use was associated with a lower response to a monetary reward,” study author and neuroscientist Mary Heitzeg, Ph.D, said in a press release. “This means that something that would be rewarding to most people was no longer rewarding to them, suggesting but not proving that their reward system has been ‘hijacked’ by the drug, and that they need the drug to feel reward—or that their emotional response has been dampened.”
That’s not all. Smoking weed might also be more addicting than you think.
“Some people may believe that marijuana is not addictive or that it’s ‘better’ than other drugs that can cause dependence,” Heitzeg said. “But this study provides evidence that it’s affecting the brain in a way that may make it more difficult to stop using it. It changes your brain in a way that may change your behavior, and where you get your sense of reward from.”
To be fair: Even if one scientific study suggests that marijuana might help your bones grow or hurt your short-term memory, that doesn’t necessarily make it true. All this research is still developing, and it’ll be a long time before we know anything for sure about weed’s effects on the human body. Still, it’s good to know where the science is heading.
Find out all the other ways—good and bad—marijuana could be influencing your health.