The stereotype of a stoner often paints a picture of someone scatterbrained and terribly forgetful. While it may be the case that cannabis has an impact on memory, the reality is more nuanced and intriguing.
There are two main categories of memory: short and long-term, which differ in what information is stored and how. Short-term memory is essentially responsible for storing temporary information and deciding what to do with it: let it go or pass it to our long-term memory, where we store information indefinitely. There is also working memory, a crucial element of short-term memory that plays a big role in how we process, use, and remember information on a daily basis. Working memory involves the ability to keep information in our mind for a short time, such as remembering someone’s phone number until you can write it down or directions to a destination that someone told you while stopped at a red light.
“There is no question that acute cannabis use affects working memory,” said Kristen Morie, a researcher at Yale School of Medicine. “If you talk to someone who is actively intoxicated, they will just, kind of, forget their train of thought.”
Researchers attribute cannabis’ memory-impairing effects to tetrahydrocannabinol (THC), which binds to CB1 receptors in brain regions that are crucial for memory, like the hippocampus. This binding disrupts the encoding of new information, hindering its storage and subsequent retrieval.
However, research also shows that cannabis can have a positive impact on neurodegenerative diseases that affect memory, such as Alzheimer’s, Huntington’s disease, and epilepsy. In mainly animal studies, when researchers used components found in cannabis, they found it could slow or even prevent the advance of these diseases – essentially through the creation of neurons.
In addition, CBD (cannabidiol), a compound in cannabis, appears to mitigate THC’s memory-impairing effects. In a 2020 study, when participants used THC with CBD, their memory performance remained unaffected, further suggesting that CBD may counteract THC’s memory-impairing effects and play a protective role. Participants’ accuracy was, on average, about the same for both tests. “So, if you give someone a [cannabis] strain with THC and a lot of CBD, they may not report as much deficit in working memory,” said Morie.
Furthermore, a 2018 review of 69 studies involving adolescents and young adults found that when those who frequently used cannabis abstained for at least 72 hours, their memory significantly improved. In fact, they performed about as well on memory tests as people who never or rarely consume cannabis.
As with all things cannabis, the complex relationship between marijuana and memory requires further investigation to fully understand its long-term implications. However, newly available research indicates that it is far less negative than previously thought.
