There is definitely some impairment long term. I think we can assume that even without this huge study. I don't think knowing that matters unless we have some scale that tells us how dramatic that impairment is.
If I compare someone who smoked all the time, but also had a rich and engaging social life with a lifelong abstainer who live a mostly isolated existence, who is going to be more cognitively capable?
There are so many inputs that feed into who we are and what we are capable of that, in all likelihood, cannabis use is likely only incidental to much larger factors like isolation, media preferences, home life, etc.
As an anecdote, the worse thing I think I've ever done for my brain, the thing that I immediately felt dumber after doing, was reading "Shadow Wolves" (Steven Segal's book). I had trouble communicating thoughts effectively for weeks after finishing it. It was like it had sucked vocabulary out of my brain. Maybe that's how cannabis leads to long term impairment. It makes you read "Shadow Wolves".
Edit: Since people are voting this, I want to add an extra warning that I was not joking about "Shadow Wolves". If you read it, you will feel dumber, and it will take time to heal the damage done. Seriously.
That is, we should assume they cause long term impairment without the need for any kind of study?
If a study comes back and says, with a high confidence, that isn't the case for this or that, great, but I think it's a safe assumption for most chemicals.
Edit: Just to be clear, I'm saying it's not enough to show something is bad, as pretty much everything is bad. It has to be bad enough to matter.
I think we are mostly in agreement - that any substance entering the body will have some effect.
The question is what effect, how much of an effect, and wether it is permanent/long lasting. Questions which require a study to answer.
Unless we're able to find twins that live largely the same lives absent the one factor, we are really only capable of sussing out the especially harmful things with long term lifestyle studies. If cannabis is as bad as sugar, then we have 40 years of back and forth to look forward to, and the answer will ultimately be: A little bit is bad, but not bad enough to matter more than how many steps you took today, or how sad or angry you were, or how late you ate dinner.
Alcohol is clearly capable of long term impairment, the debate seems to be about dose response. Nicotine is more questionable, but clearly leaves long term changes in the mind. People abstaining after long term nicotine usage will spend the rest of their lives experiencing cravings. Hell, it seems plausible long term consumption of food types has long term cognitive effects.
https://en.wikipedia.org/wiki/Self-handicapping
E.g. if someone in college does poorly because they got high all the time, maybe the reason they got high all the time was that they felt (rightly or not) that they would have done poorly anyway, and now they have the drug to blame. And maybe those who smoke a bit and still do well, do it sort of to have the excuse in reserve.
I've not much experience with cannabis, it's far less popular where I live than the US, but I can certainly see that alcohol is used as this sort of "flexible excuse", both short term and long term.
[some definitional text] The purpose of self handicapping is to protect your self identity. “I could have x, but I didn’t because of y” is the narrative story. I could have gotten an A on the exam but I didn’t because I partied instead of studied is a classic example. For it to be true self-handicapping y needs to be a choice.
This matches my personal experience as well. I’m good friends with someone that holds a high-level FAANG position and consumes weed every day. While working. Attending meetings, coding, managing large teams, the whole she-bang. It’s unbelievable. They say it “calms their thoughts” and allows them to focus.
If I tried to code while high, I would end up wasting 3 hours just fiddling with the text colors in the IDE or just space out in a wormhole of deep introspection.
Marijuana really affects people differently.
Brains are weird.
It's better than smoking, but we need to be responsible and admit that it's not exactly without risk or harm.
https://pubmed.ncbi.nlm.nih.gov/30049223/
> Conclusions: Single-dose inhalation of vaporized cannabis had no clinically meaningful positive or negative effect on airway function, exertional breathlessness, and exercise endurance in adults with advanced COPD. Clinical trial registered with www.clinicaltrials.gov (NCT03060993).
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4456813/
> The majority of studies suggest that vapourizers adequately reduce risk of pulmonary symptoms (5,14–16), although complete safety may require a regulated source of plant material, rather than ‘street’ samples, which produce ammonia (17).
> The findings suggest that vapourization reduces the delivery of toxic byproducts associated with the use of smoked cannabis. A subsequent experiment addressed exhaled carbon monoxide (CO) (14). The researchers found a statistically significant difference between the increase in CO exhaled following smoking cannabis versus vapourization. The amount of exhaled CO showed little to no increase following vapourization compared with large increases following smoking, which would be expected for inhalation of a combustion product. These findings give further evidence that vapourization reduces exposure to gaseous combustion toxins.
This isn't to say there is no risk, but if someone is going to consume cannabis it is amazingly clear that vaporizing it is safer than smoking it.
In most cases? Where in the world? In Canada at least, frequent cannabis smokers and frequent cigarette smokers are nearly disjoint groups.
No one laughed out their brains after drinking a pot of coffee.
Pun intended.
Caffeine can have pretty "bad" effects - issues with sleep, headaches, panic attacks, and all sorts of cardiovascular issues (increased heart rate, sweating, etc).
Like David Lynch, I'll stick to the coffee and cigarettes (even if the latter will probably kill me eventually, at least I can think straight)
I also have anxiety and panic attacks triggered. Though when it's over and I can think calmly, I ALWAYS see those panic attacks are my subconscious' way of telling something wrong with my life/where I'm going etc. and I need to fix things. When everything's on track I never have panic attacks regardless of the amount of substance.
In that sense it's actually telling me, in a brutal yet true way, to fix my life, by facing me feelings or thoughts that I've been subconsciously running away from.
Might not be the same case with you, surely, but this is my 2 cents.
I think regular cannabis use attracts a certain type of person. That type of person can vary in their ability and intelligence, just like any type of person. This is also true of say, hardcore fans of fantasy fiction. They all have certain things in common, but you couldn't paint all of them as "creative" or any other trait.
I'm hesitant when hearing about long term effects, even on developing brains. Both Barack Obama and Carl Sagan smoked a ton of cannabis when they were younger. And they and others really turned out fine.
This paper seems to be a meta study that combines the results from other studies. Since there were multiple methodologies it's hard to get a sense of exactly what questions they were answering.