Well, it does measurably decrease IQ. And at least in teens, this reduction seems like it may be permanent.
It might be interesting and revealing to see the correlation between casual cannabis dismissal and low or reduced IQ, but of course that goes against the popular narrative and looking for potential errors isn't where most scientists focus since that isn't super glamorous or likely to get citations from publication.
Here's a couple studies that seem to disprove that myth about weed users but, like all of these studies, they really cannot claim to be conclusive. Still better than most I've seen though:
https://www.scientificamerican.com/article/marijuana-may-not...
https://www.sciencemag.org/news/2016/01/twins-study-finds-no...
But good job cherry picking a study. Hope it makes you feel better.
You didn't cite or include a link to even one. You just tossed a load of bullshit here and hoped it would stick.
By the way... one of those cherry picked links goes to Scientific American's website. Hard to do better than that even if you are picking cherries.
Generally I expect some basic scientific literacy on HN. But of course I should have learned by now to expect science denialism when ego is at stake.
If you want a concrete source look at any of the studies that cite the twin studies, including the meta-analysis from this year.
https://www.cambridge.org/core/journals/psychological-medici...
Scientific American is not a peer reviewed publication. They are science journalism and they aren't even particularly careful about their analysis. They posted an article in 2017 claiming cannabis might make you smarter:
https://www.scientificamerican.com/article/marijuana-may-boo...
In my experience it is those who love to flout their sense of superiority by shitting on users who are arrogant. But shit can flow both ways and when I'd point out that they too use "drugs" they'd get very defensive.
Back in the 80s my cocaine using friends loved shitting on weed users. "It makes you dumb" was one of their favorite cut downs.
My alcohol drinking friends who didn't smoke weed loved to cast the aspersion that weed smokers were "drug users". When I started pointing out that alcohol was a drug too they all very loudly denied it because couldn't stand the idea that they were "drug users" too.
And along with and within those two groups are those who do prescription drugs. It was pretty strange to be accused of being a "drug user" by people taking codeine and Xanax and Quaaludes, ect.
When I pointed out the serious side effects of alcohol, both personal and to our society at large as compared to weed smokers they started shutting up about that when talking to me.
Since Colorado legalized it those kinds of encounters have been far less common, and I've certainly appreciated it. And because of that I'd probably be far less likely to be accused of being arrogant nowadays.