If I Kil Myself Today Il Never Smoke Weed Again
Does smoking pot actually brand y'all stupid?
Gut Check is a periodic look at health claims made by studies, newsmakers, or conventional wisdom. We ask: Should you lot believe this?
The Claim: Smoking marijuana does not make teenagers stupid, concludes a study in the current Proceedings of the National University of Sciences, contrary to other enquiry that linked getting stoned to impaired cognitive part in adolescents.
The Backstory: Research on how marijuana affects the developing brain goes back decades, but has heated upwards every bit more United states of america states decriminalize or legalize the drug for adults. Co-ordinate to 2015 government data, xv percent of 10th graders and 21 percent of 12th graders have used marijuana in the past month.
Nigh studies accept compared marijuana users to not-users at a unmarried point in time, and so tin't assess how marijuana changes brain role over the years; any observed differences might take always existed, marijuana or non. And all the studies have been observational — assigning some people to smoke marijuana and others to abjure would yield cleaner results only is obviously unethical. Given those limitations, it almost doesn't matter what the studies have found, simply hither's a sampling: marijuana utilize is associated with decreased intelligence, a 2007 study from New Zealand found; or with poorer memory, co-ordinate to a 1996 report of Costa Rican men and a 2002 The states study of long-term users; or with poorer attention and verbal skills, a 2010 written report reported. Other studies, but fewer, detect no long-term association between marijuana and IQ, similar this one from Canada in 2005 and this 2004 research on twins by scientists at Boston University.
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In a cardinal paper from 2012 — it was the largest and longest-running report to date, testing 1,037 people at age 13 and 38 — scientists at Duke University found a dramatic driblet in intelligence among long-term marijuana users "suggestive of a neurotoxic effect of cannabis on the adolescent encephalon," they wrote in PNAS.
As is frequently the instance, fifty-fifty reputable researchers publishing in reputable journals run brutal over the difference between correlation (two phenomena get together) and causation (one causes the other). One 2015 newspaper alleged that "regular cannabis utilize in boyhood approximately doubles the risks of … cognitive impairment." No: At virtually, such use is associated with impairment. Observational inquiry cannot rule out the possibility that a 3rd factor causes both cognitive decline and marijuana utilise.
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First Take: The new PNAS study is as well observational, but with an important twist: It zeroes in on that "third factor" possibility by studying twins, 789 in California and 2,277 in Minnesota. The twins underwent standard intelligence tests at ages 9 to 12 and once more at 17 to 20, and reported whether or not they smoked marijuana (60 percent in California and 36 percent in Minnesota did). In hundreds of cases, one twin smoked and the other didn't.
Overall, users' IQ dropped four points relative to non-users over the study period. Simply more frequent marijuana apply wasn't associated with greater IQ decline, every bit you lot'd expect if marijuana were toxic to encephalon role. And measures of and then-chosen inherent intelligence, like problem-solving, didn't fall in users; on some measures, like puzzle-solving, scores actually rose. That besides undermines the idea that marijuana impairs cognition. Instead, said co-author Joshua Isen of the University of Minnesota, it suggests that something was going on "in how much data they were absorbing," which can reverberate truancy, conscientiousness, and other factors apart from inherent cognitive ability and brain part.
The strongest evidence confronting the idea that marijuana is neurotoxic was that marijuana-using twins showed no greater IQ decline than their non-using siblings. "This fails to support the implication of the [2012] written report that adolescent use of marijuana causes neurocognitive declines," the researchers wrote in PNAS. Instead, it suggests that any driblet in brain part is non from the drug only from "factors that underlie both marijuana initiation and depression intellectual attainment" and are nowadays in both twins' lives.
That is, any spurred teenagers to commencement using too hurt their IQ.
Second Accept: Although the findings challenge the thought that marijuana employ hurts cognitive ability, it'southward not the concluding word. If the drug has simply a minor issue, this study might take been too small to notice it. And since the researchers didn't measure working memory or executive function (judgment, decision-making ability, and other higher cognitive skills), they couldn't rule out marijuana's outcome on those. Besides, some twins dropped out of the research; if they were greater users than those who stayed, the study would take missed a possible event of heavy marijuana use.
The Takeaway: This study can't rule out the possibility that marijuana hurts teenagers' brains, peculiarly in means that show up only later on decades. But information technology undermines claims that information technology does.
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Source: https://www.statnews.com/2016/01/19/marijuana-pot-weed-intelligence/
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