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Question about the long-term cognitive effects of cannabis.

silverback88

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Jan 12, 2009
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Hi,

I'm currently 21 years old and have smoked cannabis on and off probably from around the age of 15. I undoubtedly regret starting from such a young age, as I've read a number of studies that conclude that smoking cannabis from a young age (albeit younger than 15) can have permanent effects on your cognitive abilities, but my question is about long-term cognitive effects in adults.

Most of the studies I've seen (http://www.drugabuse.gov/Nida_notes/NNVol17N1/Cognitive.html and http://www.harvardscience.harvard.edu/medicine-health/articles/cognition-unaffected-marijuana-use) say that thing such as memory and concentration return to normal levels a week or so after the cessation of cannabis use, but I did read a literature review (which I, unfortunately, cannot find now) which said that smoking marijuana may have long-term subtle cognitive effects (i.e. you may not be as 'sharp' any more, and may have a harder time analyzing complex data, etc) which are not reversible.

My issue/question is this: I currently smoke cannabis at most once a week (it may be up to 4 average joints at a time). This is mostly as a replacement for alcohol (which I believe is much more harmful than cannabis) which I used to drink a lot of before (as most college kids do). My mind is my most valuable asset and I will happily stop smoking if it in anyway hurts my ability to use my brain at its maximum potential (as far as I can tell it currently doesn't affect me negatively, but I'll soon be starting a career which will require me to be at the top of my game at all time. I'll obviously not smoke during that period but I just want to be sure that what I'm doing now won't permanently make me less 'sharp').

So I wanted to ask if you guys can either post studies on long-term cognitive effects of marijuana usage (in my case at most 4 joints per week) or post your own anecdotal experiences on the topic.

Thanks!
 
I don't know how much occasional use would effect cognitive abilities because I was always a very very heavy user and it definitetly affected me a lot.

In my experience, it's not true that you get the cognitive abilities back within a week of quitting. I'd say subtle deficits persisted and it wasn't until a couple of years after I had stopped that I felt like they no longer hindered me at all. Now I am going through benzo withdrawal and I can tell you that the cognitive decifits caused by this are far worse.
 
You're going to want to check this out:


The Cannabis Re-Education Center » Forensic Cannabinology » The Hall of Mirrors » Granny Storm Crow's List - (last mirrored: 09/13/09) » SUMMARIES: » PSYCHOLOGICAL » COGNITIVE EFFECTS/ IQ

http://www.cannabisreeducationteam.com/forums/viewtopic.php?f=112&t=189




Here's a list of the articles you'll find on that page (I can't paste the URL's - they break the bluelight postform for some reason):






Cannabis use and cognitive decline in persons under 65 years of age
1999
Bottom line- "The authors conclude that over long time periods, in persons under age 65 years, cognitive decline occurs in all age groups. This decline is closely associated with aging and educational level but does not appear to be associated with cannabis use."


Cerebellar activity and disturbed time sense after THC.
1998
Bottom line- "there was a significant increase in cortical and cerebellar blood flow following THC, but not all subjects showed this effect. Those who showed a decrease in cerebellar CBF also had a significant alteration in time sense. The relationship between decreased cerebellar flow and impaired time sense is of interest because the cerebellum has been linked to an internal timing system."


Current and former marijuana use: preliminary findings of a longitudinal study of effects on IQ in young adults
2002
Bottom line- "The comparison of the IQ difference scores showed an average decrease of 4.1 points in current heavy users (p < 0.05) compared to gains in IQ points for light current users (5.8), former users (3.5) and non-users (2.6)."


Differential effects of THC- or CBD-rich cannabis extracts on working memory in rats
2004
Bottom line- "THC-rich extracts, a dose-dependent and delay independent spatial working/short-term memory
impairment was revealed... we also found no effect of CBD-rich extracts on spatial working/short-term memory"


Heavy cannabis use without long-term effect on global intelligence
2002
Bottom line- "current cannabis use "had a negative effect on global IQ score only in subjects who smoked 5 or more joints per week" and that "marijuana does not have a long-term negative impact on global intelligence.""


Marijuana does not dent IQ permanently
2002
Bottom line- "Heavy pot smokers did experience a dip in their intelligence quotient (IQ). But people who had once smoked heavily and then given up were right back up to normal, the study found. Light smokers appeared no different from non-smokers."


Neurocognitive performance during acute THC intoxication in heavy and occasional cannabis users.
2008
Bottom line- "Group comparisons of overall performance in occasional and heavy users did not reveal any persistent performance differences due to residual THC in heavy users."


Neuropsychological effects of marijuana
Bottom line- "The low dose produced generalized impairment of all mental processes (concept formation, memory, tactile form discrimination and motor function) and the effect was generalized to all modalities. The high dose resulted in more extensive impairment, again generalized...the impairment was transient"


Non-acute (residual) neurocognitive effects of cannabis use: a meta-analytic study.
2003
Bottom line- "our results indicate that there might be decrements in the ability to learn and remember new information in chronic users, whereas other cognitive abilities are unaffected. However, from a neurocognitive standpoint, the small magnitude of these effect sizes suggests that if cannabis compounds are found to have therapeutic value, they may have an acceptable margin of safety"


Review: executive functioning and cannabis use.
2008
Bottom line- "higher doses of tetrahydrocannabinol are associated to impairments in performance of nonsevere users in planning and control impulse tasks. However, chronic cannabis users do not show those impairments."
 
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From experience and 2 years of daily smoking (4-8 times a day), my mind is as clear as it was before. I still have the same problems I had before I started, and I still have the same abilities with my mind.
 
from what i remember reading in articles that mentioned a decreased in cognitive abilities in the long run it was very slight (like you said just not as sharp). I think the decrease was possible but not a sure thing and was for people who had been smoking very often for a long time. it also said that people who showed a decrease in cognitive abilities were not affected at all in their daily lives. they just performed slightly lower on certain tests and i don't think it was the same for everyone
 
NIDA is evil. Why would you believe anything a program such as that has to say?

Cannabis has no detrimental effect on cognition, regardless of length of time smoked. In fact, reuters published a study earlier this year stating that if someone smokes long term, their risk for neck and brain tumors is reduced by between 40 and 60%. (http://www.reuters.com/article/healthNews/idUSTRE5307VK20090401)

The ideas that cannabis is in any way harmful come from the prior half century of demonization and propaganda. were entering much more liberal times now, so you dont have to think about witchcraft and make believe anymore. the only harmful aspect of cannabis would be inhaling inflamed particles of the plant (vapo/cook it).

I have smoked weed since i was 14. Im in my late 20s now. I have a degree in math & cs, I lead a small programming team in manhattan, and i am actually working on some of the newest technologies and have the opportunity to be one of the first to architect some of the newest media syndication methods. my biggest hobbies include reading about theoretical physics, and neolithic-to-iron age history. on a daily basis, i cram more information and spew out more cognitive thought than anyone working at NIDA will do in their entire life... AND I SMOKE WEED EVERY DAY. In fact, I dont think a day has gone by in the last 7 years or so that I havent smoked. I also have a degree in art, could easily certify myself as a personal physical trainer, and can even do my own dishes. There is little more I loathe than the idea that cannabis makes one's brain "slow."

Maybe i missed one day of smoking here or there when the rents came to visit. Whatever. I smoke only the finest of finest dank. In fact, the only time period I havent smoked weed since i was 14 was the one year I was on probation and was being drug tested. Thats over a decade of smoke. Im the pinnacle of human health, I write and maintain a rather prestigious technology company's software platform and libraries, and I dont ever stop smoking. In fact im working from home today, vpn'ing into my dev server, and writing code right now.

Most of my friends are the same. Nutritional scientists, cardiovascular research team leaders, biochemists, neurologists, physicists, I am quite close with people in all these fields who all have been lifelong smokers. None of us have ever experienced any sort of mental decline, nor have any other friends they know of in scientific fields. Cannabis merely enhances what you want yourself to be. If you wanna sit on your couch and play nintendo wii your whole life, cannabis is not the cause of that.

Anyone into drugs that works in the sciences (which, is a lot more people than you may think) that I seem to meet is usually the same profile: daily or at least weekly cannabis smoker, 3-4 times annual psychedelic user, 1-2x annual mdma user. Ive never, ever heard anyone with a math or other science degree say that they felt cannabis slowed their cognitive function down over time, only temporal. Two of my friends are C.T.O.s for their companies, have an MS from VT, and they smoke more than me.

CANNABIS HAS NO ILL EFFECT ON YOUR COGNITION. THE ONLY THING THAT HAS AN ILL EFFECT ON YOUR COGNITION IS NOT USING YOUR BRAIN. DO NOT LET YOUR GOVERNMENT THINK FOR YOU, OR YOU WILL HAVE NO COGNITION AT ALL.
 
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If weed does effect your cognition I don't think your smoking enough anyway.
 
From experience, I certainly feel MUCH sharper after a week break. When midterms approach, I take a 2 week hiatus. It's worth it -- I feel noticeably sharper and more on my A game. I'd say when you start testing negative for weed, you are back at baseline.
 
The ideas that cannabis is in any way harmful come from the prior half century of demonization and propaganda.

I'm sorry but this is just an absurd statement. Demonization and propaganda aside, there are actual harmful effects that can result from heavy smoking.

If there weren't, how do you explain the existence of people like me? I love marijuana. I was at one time, it's biggest advocate. But I eventually had to stop smoking due to harmful effects. I'd like to know how that it is possible, if it doesn't have any harmful effects?
 
cannabis doesn't harm cognition

However I agree that people are at a greater risk of becoming drug dependant or developing bad habits with drugs if they start very young (like 15 or younger). that's just my viewpoint, however I can't justify that because there are obviously some very bright people who smoked some pot at 14.
14 is an age where kids are likely to try a number of drugs (tobacco, alcohol and pot being the most widely accepted) but obviously there are kids who start drinking at 14 who are able to control their habits and live out a healthy adolescence.

I've smoked pot daily for a year and a half since I was 17 and have no problems with the drug itself. I don't sit around thinking how I might be an Einstein if I didn't smoke pot everyday, because quite frankly i think its the pot that made me an einstein. That is a joke, but I felt it did open me up to new things I may never have encountered had I not become involved in the whole culture of psychedelics.

I think it is rather pointless to speculate how much "damage" that smoking marijuana can cause, considering I am a smart person with good intentions and people enjoy my company whether or not im smoking. And vice versa = I don't need pot to feel "normal" because I know myself enough to realize I don't need substances to keep me happy, unlike say, Amy Whinehouse who is a retarded celebrity bitch in rehab.
 
^-- what quality and quantity of cannabis would you say is mostly responsible for these effects that you have observed? i know plenty of people who smoke plenty of kind bud who do not complain of these things.

I smoked weed of all different quality, mostly kind bud but there were long stretches where I smoked mids. Quantity was 3-6 joints per day or a couple of grams of kind bud.

I know the heightened anxiety is a very common thing that happens to people who smoke marijuana every day, the other harmful effects I experienced seem more uncommon. I know a lot of people who had stomach problems in withdrawal but mine lasted for over 2 years after I stopped smoking (although they slowly improved) and now they are gone.

It's sort of the same deal with the postural othostatic hypotension, failry common for people to experience it as a side effect of cannabis but for me it lasted on after I stopped smoking and I still have it to this day, although it is much improved now.

But these effects have made me scared to smoke marijuana again, even though I miss it dearly. I would jump at the chance to get stoned again, if I could do it safely without experiencing long term health problems.
 
^-- what quality and quantity of cannabis would you say is mostly responsible for these effects that you have observed? i know plenty of people who smoke plenty of kind bud who do not complain of these things.

As much as you want it to be, weed is still a drug. It's good to be informed, it's not good to be overzealous. We all know that marijuana is not what the government used to tell us it is (ie: this is your brain on drugs), but it still can and will cause problems with abuse -- some with casual use. It's more important to become informed. Smoking anything can cause certain cancers, and it is simply absurd to think that inhaling smoke will not cause any longterm negative effects, and refuting respiratory damage is absurd. You should also take into account the variance from person to person. "knowing people" hardly is scientific evidence, I don't mean to be rude but it's the truth.

Obviously there are ways around respiratory damage (edibles, vape), but I don't think we are nitpicking here. The vast majority smokes in blunts or joint wraps, if not bowls or bongs. Lighting anything on fire and inhaling the smoke is not going to be GOOD for you.

The negative effects from weed are small, and when compared to other illicit (or even otc/legal) drugs seem negligible, but they do exist. But that falls more into the matter of "do we need a new classification for weed?" than "is weed a drug?" -- because it is.

It's best to not be 100% for either side. I truly hope you do not think that weed literally has no negative effects, chemically or physically. If that is the case, then one side has already got to you, and it makes little difference if it was the government or the otherside, it's still not true education. And if you are/were curious, I am 100% for legalization, and I would argue to my grave that the benefits from weed have outweighed any negatives they've caused me thus far, but that might not be the case for everyone.
 
I've smoked nearly daily with only a few very short breaks for the past 8 months or so. If I have weed I smoke up to two spliffs a night.
(On an aside, I'm a habitual tobacco smoker anyway so I roll with tobacco to conserve weed. I feel like this has actually led to a strong, nearly-physical addiction to spliffs. I have a bowl but I don't use it very often.)
I feel a bit mentally deficient after I've smoked in some ways. It can be harder to plan out tasks or remember to do certain things. It gives me some lack of impetus/drive, especially indica weed. As far as anxiety, I only get the social kind, and only around unfamiliar people after I've smoked. I don't smoke during the day though, before classes or work. I usually start smoking right when I get home until I go to bed. I only occasionally feel high sometimes right after I wake up, and it goes away within 15 mins or so. I never feel deficient/anxious at school or work.
On tolerance breaks, I only go through one day of being in a slightly worse mood than ordinary. I've had no strong physical effects, orthostatic hypertension, or stomach problems during either smoking or tolerance breaks.
EDIT:
I have occasional attacks of vasovagal syncope, where my blood pressure drops quickly and I often lose consciousness. These attacks have been going on since before I started smoking, but now weed seems make me more susceptible, and it's happened often from smoking for the first time after a several-day break. When I smoke normally with tolerance, I don't get sharp drops, just minor dips in my BP from standing too quickly and things like that. I'm able to control it pretty well by doing proper breathing and sitting/laying down if I feel it coming on. But this still happens when I'm sober sometimes.
 
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^ This is also something that has irked me. I have no addiction to cigerettes whatsoever, but after I have smoked weed, I crave a butt. Obviously this is a psychological tie I have created, associating the high from weed with the high from a cig. Just thought I'd throw that in, maybe you would find that info of some use.
 
just drink a red bull in the morning and one in the arvo and you can smoke all day and be as sharp as a motherfucker. plenty of vitamins and o-3s for ya brain is what you need.
 
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