Does weed cause memory loss?

Yes, weed causes memory loss. Is it only short term memory loss or is long term memory affected, too? How does weed work on the brain? We discuss here.

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Yes, you lose memory when you smoke weed, especially when you are high. But does memory loss get worse over time? We explore here.

Cannabinoid receptors and weed

Tetrahydrocannabinol (THC) is the main active chemical in marijuana. When someone smokes weed, THC rapidly passes from the lungs into the bloodstream, which carries THC to the brain and other organs throughout the body. THC half life is quite long (3-4 days) and when THC is active in the brain (1-6 hours after ingestion), THC acts upon specific sites called cannabinoid receptors, and triggers a series of cellular reactions. The two main receptors for cannabinoids are:

  • CB1 (in the brain)
  • CB2 (in the spleen and peripheral sites)

CB2 receptors are not psychoactive. But when CB1 receptors are stimulated, the chemical reaction produces both euphoria and impaired short term memory and sense of time. How and why does this happen?

Why do you lose memory when you smoke weed?

Experts are still researching exactly why and how THC works to impair memory. One theory is that cognitive effects related to memory loss (like the inability to remember words in a long sentence) may be due to a reduction in blood flow to the brain.

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Other researchers think that memory impairment occurs when you smoke weed because THC messes with the hippocampus, a part of the brain which converts information into short term memory. THC alters how information is processed in the hippocampus by changing the way sensory information gets into and is processed by the hippocampus. This causes problems with short term memory so that new information may never register – and may be lost from memory – and complex tasks that require sustained attention or concentration become difficult. When THC attaches to receptors in the hippocampus:

1. THC creates structural changes to the hippocampus region of the brain.

2. New information does not register into the brain and can be lost from memory.

3. New information may not be retrievable for more than a few minutes.

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4. There is a decrease in the activity of nerve cells.

Long term memory loss and chronic weed smoking

The link between short term memory loss and acute intoxication from marijuana has been proven. But we still don’t know the long term effects of daily smoking on memory. What we do know is that marijuana negatively affects learning and memory in chronic daily users. These adverse effects can last for days or weeks after the acute effects of the drug wear off. As a result, someone who smokes marijuana every day may be functioning at a suboptimal intellectual level all of the time.

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Marijuana can be medically helpful

Some of the effects of THC are useful in the world of medicine and can be used to treat medical conditions by blocking pain and preventing nausea. So engineers are working to create medications that attach to the same receptors as THC …without the harmful effects. Although the debate around medical marijuana seems to address the euphoric effect of marijuana, there are legitimate concerns about the health risks of smoking marijuana and cancer.

Marijuana and memory loss

In sum, the THC in marijuana disturbs your ability to process and retain new information. So it’s really not wise to study when you get high. But the long terms effects of marijuana on memory have yet to be studied. Chronic marijuana use has become a part of western culture only recently, and longitudinal studies on the cognitive impact of marijuana have yet to make causal relationships. If you have something to share, please do so here!

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Reference sources: Cellular and Molecular Mechanisms Underlying Learning and Memory Impairments Produced by Cannabinoids
What Americans need to know about marijuana
NIDA Info Facts: Marijuana
How Does Marijuana Use Affect Your Brain and Body
About the author
Lee Weber is a published author, medical writer, and woman in long-term recovery from addiction. Her latest book, The Definitive Guide to Addiction Interventions is set to reach university bookstores in early 2019.


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  1. Hi I have smoked weed for many years and I believe that if you already suffer with anxiety smoking weed does inhance the anxiety and it does affect learning and development of consideration. But on the other hand if you are overly hiper and can’t relaxs marawana works great to relax the mind and body and I can see weed helpful with cancer patients because it makes you hungry and I can see it helping with parkson desease but when it comes to helping pain in the body I don’t think it helps to much it might help you sleep but your pain won’t feel any Less because if that was the case people wouldn’t be so over medicated on drugs and have addictions to drugs that smoking weed wouldn’t even touch for the withdrawal pain . I think that it is more of a get together chill out kind of drug.

  2. i have been smoking weed for some years now. it’s relaxes me and calms me down that’s why i smoke. but for the past few years , every once in awhile i get this feelings that bothers me , and it makes me feel Paranoid, like the stuff i do feels unreal, and my memory is bad. it is currently happening to me now cause i smoke a week ago. it normally last for a few weeks sometimes a couple months and it drive me crazy cause i love smoking weed. at this point i just don’t know what to do!

  3. Thank you for the tip and every outlined information about weed. I have been trying to research about this sometime now.I can start like , i used to smoke weed when i was 14 years old upto 19, right now am 21. The kind of smoking was not that of something on a daily basis, it was just in intervals, like the kind of smoking of sometime or mostly after a long period of time maybe. Now from the time i stopped which is by the middle of 2017 was my last time to smoke , now from then i feel some how like a little uncomfortable with my brain and i fail to store information and mostly something that really scares me is that i am unable to learn fast and adapt. This is really making me feel bad, and making me to regret like almost every time.
    Now like according to the kind of effects can they be resolved or something that can be able ti restore the brain capacity and it’s functioning system?

  4. I’ve never been a chronic weed smoker but recently I’ve been doing it for 2 weeks every other day. These are the effects so far. Well before I started, I already suffered anxiety but I don’t medicate for it. When I tried the weed I of course have no worries since I am experiencing the psychedelic affect of it but the next few days after I feel like a have a constant headache, I feel more stressed out and my short term memory is shot to hell. Like right now, I just remembered I was boiling water and I did not even smoke today but I did smoke last night and now it’s making me forget things I would normally not forget. Its not like forgetting your car keys or where you parked, its like I’m forgetting some seriously important stuff. I have assignments that I’m going to fail now because my brain feels too tired to study and if I try in the post- smoking state then I will get the aura of a headache and will not be able to function. I don’t know if my short experience/experiment will help with the studies of weed but although I agree for its medical use for those that need it, I feel it recreational use will screw students over, but hey it a better alternative to tobacco and alcohol which in my humble opinion should have been off the market

  5. I’ve been smoking weed on and off since I was 13 now I’m 40 years old and I’m a Foreman in painting houses somehow I got to go back to the houses to fix other people’s mistake sometimes I get lost sometimes my boss tell me go to this house and I don’t know which house is it but I did that house 3 days ago, I’m losing my memory and I know it’s the marijuana that’s why I stopped 3 days without smoking all I want to know is if I can get my memory back if I can get my brain cells back if my mind could go back to normal or I’m going to stay like this DUMB.

  6. Hi, i have smoked weed for about 2months now and stopped. The time i ise to smoke i was ok but since i decided to quit, I’m now experiencing some changes in headache and sometimes don’t remember my area but i talk normally. Please what could be the problem

  7. Hello, i am a 20 old year teen i been smoking weed from 15 year and until now i never had problema i am a programmer infact when i smoked weed it helped me with focusing on little things that i didn’t have thia when i am at normal stage but theese last days i am forgeting some usual things for example i take phone put on packet than aftwr some minutes i will think did i put the phone on pocket or not ? But only on small things maybe i am not give to much focus but i never had this problema before. I smoked daily 1-2 joint per day sometimes 3 and never pause but now i paus3 on weed to see if my remember will come back on thia little things its my 4 day without smoking now but its the same i am thinking i need more days to wait because i smoked it daily. Any suggest or information from your side would be helpfull thank you. Best regards UCA.

  8. My boyfriend smokes everyday and comes in talking stupid smells like shit and can’t remember from one min to the next what he’s doing and he’s been like this for 6 years. I am sick of it and realize he ain’t ever going to change I need help to get him out of my life. I’m addicted to this destructive relationship that is killing me every day. Where do I get help.

    1. Hi Katina. Have you tried Nar-Anon. This community helps family and friends of addicts recover from the effects of living with an addicted relative or friend.

  9. Pls I smoked weed for over 3 months now but am still feeling high like I’ve lost my mind and sometimes I feel like something is walking in my head and confused. pls am I going to remain like this forever

    1. Hi Algaray. Call 1-888-503-1835 for a toll-free and confidential marijuana helpline available 24 hours a day, 7 days per week. You will be greeted by a professional and understanding consultant who will assist you in understanding the types of marijuana addiction treatments available to you.

  10. Hello, I would like to know which were the scientific papers you used to make and justify this article. And it would be great if you could share them to me. Thanks 🙂

  11. I have yet to receive a reply about my ongoing battle with short term memory loss which I attribute to my heavy drug use, primarily marijuana which I smoked several times daily, among other drugs, for 14 years and ADD. Is there a connection? I haven’t had any drugs and very little alcohol in the last 27years. But people I talk to one day at my store I can’t remember the next day, and it’s not a busy store.

  12. I’ve been smoking weed 4 a very long time and I am supposed to be a junior but I am a freshman then I started smoking weed so now I am unable to pass now cause my memory is very messed up. it’s hard to memorize things. I won’t even be able to pass high school now cause I got to take the 4 required tests in order to graduate. Sometimes I just think about giving up on life cause if I cant pass high school I will be working at McDonald’s for the rest of my life and that will cause me to struggle. I hate what I did. I loved the feeling that it had but now I’m disappointed in myself. Sometimes I just think about eating raw meat and just not going to school cause it would be a waste of time for me.

    1. Hi Austin. Don’t give up. There are treatment for marijuana addiction. Call 1-888-503-1835 for a toll-free and confidential marijuana helpline available 24 hours a day, 7 days per week. You will be greeted by a professional and understanding consultant who will assist you in understanding the types of marijuana addiction treatments available to you.

  13. I’ve been smoking medically for about 3 months, (not prescribed, will go for green card in few months when we get it) pretty sure I’ve actually cured my short term memory loss, I’ve noticed ive been realizing a lot of things I’ve forgotten while still remembering what i did earlier. Ive found the root to my anxiety which is i second guess myself so much i didn’t realize i was doing it, I’ve gotten control of my anger and am now more peaceful. If done every day, it really can help, yes i started out having fun until i realized it was helping me. I hope this helps anyone.

  14. Hi
    I’m looking for answers to my long term effects that I get the feeling times I’ve smoked.
    The first time I smoked, I woke up with the sensation of still being high, or at least not in my own body sort of speaking.
    It has been like this for 4 years now and I still feel like my whole life is a like a movie that I take part in, and meanwhile look down upon as if I am dreaming…
    I have still not found any explanation involving these sort of long term issues from smoking weed.
    Thanks for hearing me out.

  15. i think overdose of weed can couse some memory problems for even weeks i have that problrm but i know i need some time and my brain will be the same i remember most of the things that happened while i was high, but still during the time of high i was scearde that i wont be able to think talk understand things and rememver it now everything is fine but not the same and i know it needs some more time to become everything same

  16. I start smoking POT when I was 19 and now I’m 21. But before I start smoking it I already had a short time memory loss. I used to like smoking it before when I still have a hard job that I over fatigue my body. So before I go to sleep at night I smoke it to calm and relax my self for the long hard working day. And it helps me to get up again in the next day.. But when I torn 20 i noticed that my memory is getting hard to recover some names of my old friends and some words that I just read about an our ago. But I ignored it and keep smoking. And in some moment I stopped smoking pot for a couple of months like 4- 6 moth I guess, cant remember exactly, and resumed smoking last month. I smoke again everyday and now I stop again for a week.. In this past weeks I noticed again that it’s affect my short and long term memory, like I read a word just a couple of minutes ago or something that told me by someone and I’m getting hard to recover what are those. So now I’m getting kind aware by this happenings that’s why I ended up searching if marijuana can affect our short/long time memories.. My question is: Is there anything I can do to prevent or to stop the losing of my short term memories? if there is please share it here. It will help me because I’m still in college and it’s hard to study and take exams when you can’t remember some answers though you review well. Thank you for your response.

  17. I’ve read all the articles about memory loss and in my case Medical marijuana. I however have been off the marijuana for nearly a month. Besides my spasms returning, and loss of appetite, I have found my memory getting worse, to the point I’m getting very concerned. I smoked daily for the pain, spasms and appetite. All which have complicated things for me personally. However my Dr all of a sudden pulled my pain meds for a week until I quit, which was very uncomfortable and nearly put me in the hospital as I have a heart condition. So you can say whatever you must, but my medical marijuana was very helpful to me. And needless to say that it was easier to quit than the drugs I’m on. I’m curious about what you think about my situation.

  18. I smoked pot every day for 30 years. I quit three months ago when I finally realized, through acquaintances, that I had forgotten a great deal. But being retired and living alone, of course it didn’t bother me … at the time. So I performed an experiment over the last couple of weeks, and confirmed the short term memory loss – which of course compounds into the long term, over the long term. And realized I had not been performing at maximum mental capacity. Although I agree it is undoubtedly effective medicinally. But be careful with it, be prepared for forgetfulness. Then I found your site.

  19. I was a heavy daily pot smoker for 16 solid years, and did other illegal drugs along with marijuana such as cocaine, opium, meth, Quaalude, LSD, hashish, other barbiturates, other uppers, angel dust, and freebased coke, along with lots of alcohol. I started at 18 and quit at all drug use at 32 when I became a committed follower of Christ.

    Now I’m 57 and can’t seem to remember anything short-term, especially people’s names and oftentimes their faces. This in addition to the almost vacant memories of my past, especially during my years of drug use. I suffer from chonic depression as diagnosed by a noted psychologist who also affirmed I had ADD (non hyper), and I suffer from non-weight related sleep apnea.

    So, how much of this loss of memory, especially the current short term memory loss (even though I’ve been drug free for 25 years) is due to smoking weed or doing the other drugs?

  20. The first time I smoked the green, I passed out on the floor twice. I could say, it messes with our consciousness. I have been doing a long-term smoking ganja spree. & I didn’t mess with any lower class. Now if I smoke, I instantly forget what I do, as if I don’t remember doing it. I do feel more ignorant, because I have to check my grammar now a days. I do it to reread my sentences to make sure It seems understandable. Unless that is me trying to perfect things. I’ve had laced weed before and have done drugs. My visual color perception is off. Because in a dim light, in unknown areas, I need a flash light. I also have light sensitivity and gained migraines. This memory loss theory, I can believe it. But I think weed aggravates it.

  21. In case you need it:
    “In many shamanic societies, if you came to a medicine person complaining of being disheartened, dispirited, or depressed, they would ask you one of four questions: When did you stop dancing? When did you stop singing? When did you stop being enchanted by stories? When did you stop finding comfort in the sweet territory of silence?” -Gabrielle Roth

  22. The marijuana increases different chemicals in the mind you’ve got to try to get back to normal feelings or else it will kill you Be aware that if you can’t remember how will you ever know how to feel pleasant without anxiety again and smart again. You’ve make yourself feel better w/o the drug by remembering how to feel happy around others and share your happiness and personality with others

  23. I’m only 15 and I smoke weed. I started at 14 but it was like once in a bluemoon, just wanted to witness the feeling of getting high, and I did. But the main reason why am I hear is that I got high and when I get high it tskes 3 hours for me to get better, but the weed I had made me recover after days, and at times I used to get the high feeling back after couple of days. Then 6week later on I found marjuana and it was a month old I decided to smoke it and from then, its been a week btw, I’ve been getting headaches, my mind blank, I feel dumb and I can’t sleep at night. Can someone help me plzzz

  24. This “drug” ( plant) doesn’t cause your memory loss, you do! You choose to get “high” not medicated.. It’s your choice whether you act a fool or stay calm and collected whether you smoked to forget it all, or to absorb and learn. In fact some studies show that in taking cannibis can help stimulate brain activity and reform brain cells. It’s all up to the “user” what your going to use it for.

  25. I am 75 and have been smoking a few pipefulls daily since 1996 as a segue for quitting a 40 year cigarette addiction and for arthritic pain relief despite 2 hip replacements and recently, a shattered humerus I am also BrCa positive (Breast cancer), and have had a right lung lobectomy in 2007.
    I am monitored closely by my pulmonologist, getting bi-annual ct/scans and yearly PET scans.
    My increased memory loss, inability to remember verbal information (if I read it, I remember it),
    and loss of train of thought in conversation have been of great concern despite friends commiserating, A 10- session cognitive training course given by a neurologist was fun but not helpful. My brain scan is normal.
    My” C.R.S.” affliction was blamed on the length of time I was under anesthesia (8 hours for my arm in 2007) during all my surgeries. Since there was no research on pot smokers of my generation, I kept my toking a secret. My research into lung cancer centered on my being BrCa Pos. ( my mother had breast cancer twice), and I found only one research paper from Japan regarding BrCa gene & lung cancer ( inconclusive).
    Friday, after my ct-scan, my pulmonologist called to tell me a tiny spot was found on my left lung
    and I am scheduled for a PET scan this week. So, is it BrCa related or Cannabis related ?
    I was diagnosed COPD/emphsyma – and suffered from mild sleep apnea and shortness of breath.
    After recently losing 20 lbs and working out at my pulmonary gym- my breathing is perfectly normal for the first time in my since I quit smoking menthol cigarettes.
    As for my evening pot smoking- my hoarseness is quite pronounced,

  26. I am struggling to cut down as well from memory and organizational and focus issues. If pot is what is causing my inability to retain anything and to organize and focus, I could use help on stopping I recently quit my stressful job after 29 yrs because I couldn’t organize focus or remember stuff at work.

  27. when I have long term use of marijuana I have extreme memory loss, enought that it worries me…will my memory come back once I stop smoking?

  28. i have been smoking ciggrate since i was 14 yrs old and now i m 21yrs i thing it is creating problems on me.i cant sleep well,cant concentrate at my study and couldnt remember what i studied for a long time.i tried very much to give up but still i couldnt.can you help me to stop it?and also plz tell me if i give up smoking,can i get rid from these problems?

  29. Hi Kelly. In terms of reducing the harm on your body, you might consider seeking some alternatives. One would be to cook with marijuana. The other would be to seek a prescription for the drug dronabinol, which contains tetrahydrocannabinol, or THC, the same active ingredient as in marijuana plants. Both will help cut back on the damage smoking causes to your lungs.

    In terms of anxiety, however, you may be in a loop. Marijuana can increase anxiety. On the other hand, psychotherapy is very useful in treating anxiety. When you’re ready to stop using weed (THC)…start by seeing a psychotherapist twice weekly for support. Because you’re unemployed, do you work with a social worker? Perhaps you can get some referrals to services through him/her?

  30. I have been smoking marijuana since I was 13 yrs old and I am now 27yrs old. I have 4 children and busy life style . I have been unemployed for a while now and in process of going to re take my lna licence test to renew my licence and get back to work . its been 3 yrs since i worked as lna. I am very worried and stressed all the time i suffer from adhd , axiety and at times depression my worst symptoms have been axiety and my OCD issues. I have to clean constantly and such. My marijuana use has never been a problem untill a bout 5 years ago. I did a sleep study and dr had explained due to my marijuana use i was hurting my brain and i do suffer from memory loss now. My worryness is helping with me wanting to really stop smoking also due to you have to drug test anyways to get a good job now and i dont want to fail getting back into my career. I have pleaded with my dr but she doesnt have any suggestions other then just stop and she wont prescribe my adhd medicine to me untill i can pass a urine sample that has yet to happen although at times i successfully do stop using for about a week 7 days and then i go insane and feel depressed emotions run high and axtiety gets to me and i smoke. i have now in last 3 years mainly smoke at night or early morning and i feel so much better and feel like i can function right .. when i dont smoke thats when i feel worse .. What do I do?? i want to stop .. i hate that i cant smell or taste much lately my chest hurts more and i have trouble breathing lately. i need to get passed the axeity part that holds me back from just not smoking. I wont get a job either when i take my lna test if i dont stop. I have children full time i cant leave them and i cant fail them . any ideas to shed on my problem? and any advise would be great . i am searching for support groups that specify with marijuana use but all i can find is AA .

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