People who consume tetrahydrocannabinol (THC) are more likely to have false memories and to struggle completing everyday memory tasks like remembering to do something later. The corresponding study was published in the Journal of Psychopharmacology.
"Most previous studies have only looked at one or two types of memory, like recalling lists of words,” said senior author of the study, Carrie Cuttler, an associate professor of psychology at Washington State University, 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,” she added.
Cuttler and colleagues conducted a randomized, double-blind, placebo-controlled study to better understand which aspects of memory are affected by acute cannabis use. They recruited 120 regular cannabis users who were randomly assigned to vaporize 20 mg THC (a moderate dose), 40 mg THC (a high dose), or a control (flower containing no THC), before taking a battery of memory tests.
Ultimately, the researchers found that THC negatively affected multiple aspects of memory, including verbal memory, visuospatial memory, event-cued prospective memory, and temporal order memory. The most pronounced effects were on source memory—determining where information comes from, be it a trusted source, a conversation, or something encountered online—and on false memory.
"I found it was really common for people to come up with words that were never on the list. Sometimes they were related to the theme of the list, and sometimes they were completely unrelated,” said Cuttler.
Both moderate and high doses affected memory in a similar way.
"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,” concluded Cuttler.
Sources: Science Daily, Journal of Psychopharmacology
