This article originally appeared at https://qz.com/1457030/what-weve-learned-about-the-effects-of-weed-since-it-was-legalized?linkId=59421172
It’s been six years since Colorado and Washington legalized marijuana, and scientists keep on unearthing more data on the effects of the drug.
Just this week, research presented at the 2018 meeting of the Society for Neuroscience showed that marijuana use in teenagers affects the development of areas of the brain responsible for self-control and planning. And a study published in the Journal of Clinical Psychiatry the week before showed that one month’s abstinence from cannabis improves the memory of adolescents and young adults.
The news isn’t all bad. Research published last year also found that cannabis relieves some of the symptoms of Parkinson’s disease and that people who smoke more weed also have more sex. Further studies on cannabis have offered increasing evidence that it can alleviate chronic pain and insomnia.
There hasn’t been research that says definitively whether marijuana is a major health risk or a panacea. In part, that’s because academics still face a lot of regulation and restrictions on researching the drug, and in part because we’re still finding out new information concerning all manner of drugs, even those that have been legal for decades.
On a broader public-health level, the scientific evidence suggests we’re still figuring out the effects of the legalization of marijuana. The studies to date indicate that a small number of people likely make up the majority of problem users. As Vox reports, a 2014 study of the marijuana in Colorado found the top 29.9% heaviest users in Colorado accounted for 87.1% of the demand. Of course, not all of those smoking a lot will have a problematic relationship with cannabis, but a small percentage of addicts will certainly make up a significant portion of the weed market.
In recent years, several articles have highlighted the effects of cannabis addiction, which is estimated to impact 9% of all overall users, and which was often ignored as the legalization movement emphasized the notion that weed is harmless. Keith Humphreys, a professor of psychiatry and behavioral sciences at Stanford University, warned in an Atlantic feature on the risks of marijuana, “In large national surveys, about one in 10 people who smoke it say they have a lot of problems. They say things like, ‘I have trouble quitting. I think a lot about quitting and I can’t do it. I smoked more than I intended to. I neglect responsibilities.’”
Growing numbers of states are opting to legalize marijuana and, judging by the evidence so far, there haven’t been truly disastrous consequences. But we’re still uncovering evidence on how marijuana affects us and, chances are, we’ll be figuring out the details for a while yet.