Although the "Reefer Madness" years may be far behind us, we're still surrounded by marijuana paranoia. However, a new study suggests that the biggest health risks of pot use are still pretty minimal — and your teeth may bear the worst of it. For the study, published online this week in JAMA Psychiatry, researchers looked at a group of 1,037 people born in New Zealand. The researchers followed up with these participants from age 18 until they were 38. They kept track of participants' marijuana use — hilariously measured in "joint-years" — as well as their tobacco use and 12 measures of overall health. Their results showed that cannabis use had no effect on all but one of the 12 health measures. More specifically, smoking pot didn't influence blood pressure, cholesterol levels, or inflammation, but it did significantly worsen people's periodontal health. Using tobacco, on the other hand, was associated with poorer scores on eight of those health measures.
So what does that actually mean? "In general, our findings showed that cannabis use over 20 years was unrelated to health problems in early midlife," the study authors write. "Clear evidence of an adverse association with cannabis use was apparent for only one domain, namely, periodontal health." This is great news for cannabis lovers, but the study does have limitations. All of the marijuana use in the study was self-reported, and it's not clear how great humans are at accurately remembering how much or often they smoke pot. There's also the fact that this study only includes data for participants up to age 38, so we can't make any claims about how true these findings are for weed users beyond that age. And, as The Washington Post points out, the study doesn't consider the possible mental health effects of marijuana. The lead author on this study, Madeline H. Meier, PhD, even used the same dataset that was used in an infamous 2012 study to suggest that chronic pot use may lead to a decrease in IQ. But, remember, subsequent studies have failed to find that same strong effect (and it's probably a more complicated story than we think). More than anything else, this study suggests that we still have plenty of research to do.