Monday July 28th 2014

Does weed cause memory loss?

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.

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.

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.

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!

We love your feedback!

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

Photo credit: Loving Earth

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7 Responses to “Does weed cause memory loss?
Kelly Robinson
3:42 pm April 24th, 2013

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 .

8:45 am May 9th, 2013

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?

niranjan
5:26 pm July 20th, 2013

i have been smoking ciggrate since i was 14 yrs old and now i m 21yrs old..now 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?

megan
6:08 pm August 27th, 2013

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?

sarah k
11:56 pm December 18th, 2013

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.

sarah k
11:57 pm December 18th, 2013

I am hoping that by decreasing or quitting that my memory will come back. I am 60 and I worry that I am getting dementia.

Elle
8:34 pm January 12th, 2014

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,

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