Cannabis is often known for its relaxing effects, but scientists are increasingly studying how it affects the brain, especially memory. A new study from Washington State University suggests that cannabis may change the way memories are formed and recalled.
The research shows that people who consume THC, the main psychoactive substance in cannabis, may be more likely to remember things incorrectly and may struggle with everyday memory tasks. The findings were published in the Journal of Psychopharmacology.
Memory plays a central role in daily life. People rely on memory to remember appointments, follow conversations, recall where they placed objects, and complete tasks later in the day.
When memory does not work properly, it can affect work performance, relationships, and personal safety. For this reason, scientists are very interested in understanding how substances like cannabis influence different types of memory.
Many earlier studies have already shown that cannabis can affect short-term memory, but most of that research focused on only one or two specific types of memory. The new study is different because it looked at several memory systems at the same time.
According to Carrie Cuttler, an associate professor of psychology at Washington State University and the senior author of the study, this research provides a more complete picture of how cannabis affects memory across many areas of thinking.
To conduct the study, researchers recruited 120 adults who were regular cannabis users. The participants were divided into three groups in a carefully controlled experiment. One group inhaled cannabis that contained no THC, which served as a placebo.
The other two groups inhaled cannabis containing either 20 milligrams or 40 milligrams of THC. Neither the participants nor the researchers knew which treatment each person received at the time, which helped ensure unbiased results.
After consuming the assigned substance, the participants completed about one hour of memory tests. These tests measured several different types of memory. Some tasks examined verbal memory, such as recalling lists of words.
Other tasks tested visuospatial memory, which involves remembering locations or visual patterns. The researchers also tested prospective memory, which is the ability to remember to perform actions in the future. In addition, they examined source memory, false memory, episodic memory, and memory for the order of events.
The results showed that participants who consumed cannabis performed worse than those who received the placebo in many of the tests. In fact, cannabis use affected 15 out of the 21 memory measures examined in the study. This suggests that THC can disrupt many types of memory at the same time rather than affecting just one specific area.
One of the most striking findings involved false memories. In one test, participants listened to lists of words that were all connected by a common theme. However, the key word that represented the theme was never actually spoken.
Later, participants were asked to remember which words had appeared on the list. People who had consumed THC were much more likely to say they remembered hearing words that had never been presented.
Researchers explained that this result shows how cannabis can make the brain fill in gaps in memory with incorrect information. In some cases, participants reported words that were related to the theme of the list, while in other cases the words they recalled were completely unrelated.
Another type of memory affected by cannabis was source memory. Source memory helps people remember where they learned something.
For example, it allows someone to remember whether a piece of information came from a news article, a conversation with a friend, or a social media post. Participants who consumed cannabis had more difficulty identifying the source of the information they had learned earlier.
Problems with source memory can have important consequences in real life. For example, eyewitness testimony in legal cases relies heavily on accurate memory. If memory becomes distorted, people may unintentionally report incorrect details about events.
The researchers also observed problems with prospective memory. Prospective memory involves remembering to perform actions in the future.
Examples include remembering to take medication, attend meetings, or stop at the store on the way home from work. Participants who consumed cannabis were more likely to forget tasks they were supposed to remember later in the experiment.
Interestingly, the researchers did not find a major difference between the group that consumed 20 milligrams of THC and the group that consumed 40 milligrams. This suggests that even moderate amounts of THC may significantly affect memory.
One type of memory known as episodic content memory, which involves recalling personal experiences, did not show a strong effect in this study. However, the researchers emphasized that more studies will be needed before drawing firm conclusions about this aspect of memory.
The findings are especially important because cannabis use has increased in many places where laws have become more relaxed. In parts of North America, including Washington State, cannabis use is now common among adults. Despite this growing use, scientists still have limited information about how cannabis affects thinking and memory in everyday situations.
Another reason research has been limited is that cannabis has long been classified as a controlled substance under federal law in the United States. This classification has historically made it more difficult for researchers to conduct detailed studies.
When reviewing these findings, it is important to recognize both the strengths and limitations of the research. The study used a well-controlled experimental design and examined several memory systems at once, which provides valuable insight into how cannabis affects cognition.
However, the participants were all regular cannabis users, so the results may not apply exactly the same way to people who rarely use cannabis.
Overall, the research suggests that cannabis intoxication can interfere with several types of memory that people rely on in their daily lives. The increased likelihood of false memories and difficulty remembering tasks could have practical consequences, especially in situations that require careful thinking or accurate recall.
The researchers emphasize that the goal of the study is not to judge cannabis use but to help people understand its effects more clearly. By improving scientific knowledge about cannabis and memory, researchers hope to help individuals make more informed decisions about the risks and benefits of using the drug.
If you care about cannabis, please read studies that what you need to know about cannabis and heart attack, and CBD from cannabis may help inhibit COVID-19 infection.
For more information about cannabis, please see recent studies that medical cannabis could help reduce depression, and results showing this stuff in cannabis may protect aging brain, treat Alzheimer’s.
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