Many people smoke pot to relax and forget about their problems, but scores of studies show that chronic weed use impairs short-term memory. Some research has found that the more pot you smoke, the worse your memory will function.
Marijuana is especially damaging to working memory, which is important for concentration and learning.
Working memory is like a mental sticky note that allows the brain to hang on to new information and work with it for a few minutes or a few hours. It’s what allows us to recall a phone number, perform mental arithmetic or remember a set of directions as we navigate to a new location.
Long-term marijuana use can also damage a person’s verbal memory.
A 2016 study published by JAMA Internal Medicine found that middle-aged people who smoked marijuana daily for five years or longer performed worse on word memory tests than those who don’t smoke pot. The more weed they smoked, the poorer their word recall was.
How Weed Causes Memory Loss
Scientists are still sorting out exactly how marijuana causes memory problems, but THC, the primary psychoactive ingredient in marijuana, appears to be the culprit.
According to the National Institute on Drug Abuse, studies on rodents have shown that THC alters the hippocampus, the part of the brain that processes information and creates memories.
Deterioration of the hippocampus is what causes age-related memory loss, and THC appears to accelerate this process. Rats that received THC every day for eight months lost as many brain cells in the hippocampus as rats twice their age, according to NIDA.
Shedding more light on the process, a 2012 study cited in an article by the journal Nature found that THC weakens the connections between brain cells in the hippocampus.
Can You Black Out From Weed?
Marijuana typically doesn’t cause the same sort of memory loss as binge drinking.
When people drink a lot of alcohol over a short period of time, they can experience episodes of amnesia known as alcohol blackouts. Following an alcohol-induced blackout, a person may have patchy memories of what happened during a night of heavy drinking. Some people remember nothing at all.
The memory loss associated with marijuana is more subtle. A person who is stoned may have trouble remembering things they learned in school or forget where they’ve left things. The person may feel fuzzy-headed and unable to concentrate.
These common symptoms of marijuana use have contributed to the stereotype of the forgetful, hazy and unfocused marijuana user.
Over time, heavy marijuana use can take a serious toll on the brain. Adolescents who are heavy marijuana users can even lose IQ points by adulthood, according to 2012 study published in Proceedings of the National Academy of Sciences of the United States of America.
Memory loss may be more severe if a person drinks alcohol while smoking pot. Combining the two drugs is sometimes referred to as getting crossfaded. Individuals who binge drink while high can experience amnesia.
Using more potent forms of marijuana, such as oils, may increase the potential for serious side effects, including a temporary loss of consciousness.
Butane hash oil, which is also known as shatter, budder, wax and honey oil, is a concentrated marijuana product with five to 10 times the THC content as a normal joint. Individuals usually inhale the vapors of these oils through a practice known as dabbing.
Marijuana concentrates have caused some people to faint. Two of the six marijuana users that researchers interviewed in a 2016 article published in the Journal of Psychoactive Drugs said they passed out the first time they dabbed butane hash oil.
Is Weed-Related Memory Loss Reversible?
Memory problems are one of the most common reasons people seek treatment for marijuana addiction or dependence. Fortunately, research suggests that weed-related memory deficits aren’t necessarily permanent.
A 2013 study in the journal of Substance Abuse and Rehabilitation noted that some individuals have experienced a gradual improvement in memory once they quit using weed. Within 48 hours to a month of sobriety, in fact, some regular marijuana users’ memory function had returned to normal.
If you or someone you love is suffering from memory problems related to weed use, marijuana addiction treatment can help break the cycle of addiction.
Medical Disclaimer: DrugRehab.com aims to improve the quality of life for people struggling with a substance use or mental health disorder with fact-based content about the nature of behavioral health conditions, treatment options and their related outcomes. We publish material that is researched, cited, edited and reviewed by licensed medical professionals. The information we provide is not intended to be a substitute for professional medical advice, diagnosis or treatment. It should not be used in place of the advice of your physician or other qualified healthcare provider.
View Sources
- Auer, R., Vittinghoff, E. & Yaffe, K. (2016). Association Between Lifetime Marijuana Use and Cognitive Function in Middle Age. Retrieved from https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/2484906
-
- Costandi, M. (2012, March 1). How marijuana makes you forget. Retrieved from https://www.nature.com/news/how-marijuana-makes-you-forget-1.10152
-
- Ingraham, C. (2016, February 1). Heavy pot use can permanently damage short-term memory, study shows. Retrieved from https://www.seattletimes.com/nation-world/study-says-heavy-marijuana-use-can-damage-short-term-memory/
-
- Crane, N. et al. (2013, June). Effects of Cannabis on Neurocognitive Functioning: Recent Advances, Neurodevelopmental Influences, and Sex Differences. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3593817/
-
- Gathercole, S. & Alloway, T. (2013). Understanding Working memory: A Classroom guide. Retrieved from https://www.mrc-cbu.cam.ac.uk/wp-content/uploads/2013/01/WM-classroom-guide.pdf
-
- Hall, W. & Lynskey, M. (2016, March). Long-term Marijuana Use and Cognitive Impairment in Middle Age. Retrieved from https://jamanetwork.com/journals/jamainternalmedicine/article-abstract/2484901?redirect=true
-
- Han, J. et al. (2012, March). Acute Cannabinoids Impair Working Memory through Astroglial CB1 Receptor Modulation of Hippocampal LTD. Retrieved from http://www.cell.com/cell/fulltext/S0092-8674(12)00142-0
-
- Meier, M. et al. (2012, October 2). Persistent cannabis users show neuropsychological decline from childhood to midlife. Retrieved from http://www.pnas.org/content/109/40/E2657
-
- Miller, B., Stogner, J., & Miller, J. (2016, January). Exploring Butane Hash Oil Use: A Research Note. Retrieved from https://www.researchgate.net/publication/291516855_Exploring_Butane_Hash_Oil_Use_A_Research_Note
-
- National Institute on Drug Abuse. (2013, March). Marijuana’s Lasting Effects on the Brain. Retrieved from https://www.drugabuse.gov/about-nida/directors-page/messages-director/2013/03/marijuanas-lasting-effects-brain
-
- National Institute on Drug Abuse. (2018, February). What are marijuana’s long-term effects on the brain? Retrieved from https://www.drugabuse.gov/publications/marijuana/what-are-marijuanas-long-term-effects-brain
-
- National Institute on Drug Abuse. (2018, February). What is marijuana? Retrieved from https://www.drugabuse.gov/publications/drugfacts/marijuana
-
- Nir, S. (2016, May 12). Chasing Bigger High, Marijuana Users Turn to ‘Dabbing.’ Retrieved from https://www.nytimes.com/2016/05/13/nyregion/chasing-bigger-high-marijuana-users-turn-to-dabbing.html
-
- Schoeler, T. & Bhattacharyya, S. (2013). The effect of cannabis use on memory function: an update. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3931635/
-
- Solowij, N. & Battisti, R. (2008). The Chronic Effects of Cannibas on Memory in Humans: A Review. Retrieved from http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.334.3701&rep=rep1&type=pdf
-
- Smith, M. et al. (2014, March). Cannabis-Related Working Memory Deficits and Associated Subcortical Morphological Differences in Healthy Individuals and Schizophrenia Subjects. Retrieved from https://academic.oup.com/schizophreniabulletin/article/40/2/287/1944376
-
- The JAMA Network. (2016, February 1). Long-Term Marijuana Use Associated with Worse Verbal Memory in Middle Age. Retrieved from https://media.jamanetwork.com/news-item/long-term-marijuana-use-associated-with-worse-verbal-memory-in-middle-age/
-
- White, A. (2004, July). What Happened? Alcohol, Memory Blackouts, and the Brain. Retrieved from https://pubs.niaaa.nih.gov/publications/arh27-2/186-196.htm
