According to a new study from Washington State University (WSU), researchers discovered that cannabis intoxication impacts the way memories are recalled, along with specifically impacting prospective memory, the capacity to remember tasks needed at future dates.
The study was published in the Journal of Psychopharmacy, and explores the impacts of cannabis on memory at a deeper level compared to previous studies. The results revealed that while cannabis impacts recall, it can also impact the memories that are relied on at a daily level, such as conversations, appointments and the origin of information that they do remember.
“Most previous studies have only looked at one or two types of memory, like recalling lists of words,” said Carrie Cuttler, senior author of the study and an associate professor of psychology at WSU in a press release. “This is the first study to comprehensively examine many different memory systems at once, and what we found is that acute cannabis intoxication appears to broadly disrupt most of them.”
The study also examined the impacts of dosage, and found no substantial difference between participants who consumed 20 milligrams of THC compared to those who consumed 40 milligrams. According to researchers, this reveals that lower levels of THC may lead to disruptions of memory.
During the study, Cuttler and co-author Ryan McLaughlin, an associate professor in the Department of Integrative Physiology and Neuroscience at WSU, observed 120 “regular cannabis users” and provided them, at random, with placebo cannabis, 20 milligrams of THC or 40 milligrams of THC. Then, participants completed tests that measured a variety of memory of classifications including verbal, visuospatial, prospective, source, false, episodic content and temporal order.
Those who consumed cannabis performed the test tasks worse than those who had been given the placebo, revealing that cannabis impacted most of the memory tests. Most impacts were seen in false memory and source memory, the ability to accurately recall information and remember where it originated from. During testing, participants were provided with lists of related words, excluding the key word that tied them together. Participants who consumed cannabis were more likely to remember related and unrelated phantom words; words that had never been presented during the initial test.
“I found it was really common for people to come up with words that were never on the list,” Cuttler continued. “Sometimes they were related to the theme of the list, and sometimes they were completely unrelated.”
Similarly, researchers found that those who consumed cannabis struggled with identifying the source of information that was previously learned.
“We’re living in a state where cannabis use is very common, but there’s still a lot we don’t know about its acute effects. The goal is to help people make informed decisions about the risks and benefits,” Cuttler said.