United States: According to a recent study, heavy marijuana use may impair the brains of young adults, especially their short-term working memory.
The results published in JAMA Network Open on January 28 showed that heavy marijuana use was associated with less brain activation in tasks that tested cognitive ability for short-term memory, as reported by HealthDay.
Cognitive Impact of Cannabis Use
“Lifetime heavy cannabis use history was associated with lower brain activation related to working memory, with a small to medium effect size,” concluded the research team led by Joshua Gowin, an assistant professor of radiology with the University of Colorado Anschutz Medical Campus.
The previous research consensually related the use of marijuana with decreased memory, planning, decision-making, and social ability. However, previous attempts have generally had very few participants who were regular or heavy initiators, the team argues.
I think alcohol has worse effects in the short term while weed has worse effects in the long term.
— Res (@ResTehBestMaybe) January 26, 2025
The negative effects of booze are well-documented.
The negative effects of weed, however, are less accurately known.
Memory loss, low motivation, higher risk of schizophrenia… https://t.co/Zo0jWv2mcQ
Memory and Brain Function Affected
MRI scanning and cognitive tests were conducted on more than 1,000 young adults and analyzed as the centerpiece of a mega-research project on the lingual mapping of the human brain.
According to researchers, participants were administered various brain-scanning MRI techniques while they performed seven assorted brain tasks.
Heavy users were defined as those who had used cannabis 1,000 or more times, or approximately 9% of the participants.
Key Findings
There were also moderate users, defined as those who had sampled weed 10 to 999 times, and they made up 18% of the subjects: on the other extreme were the non-users.
The study has shown that some brain regions were less activated during the working memory task among heavy users of marijuana.
These include the anterior insula, which relates to emotion processing, and the medial prefrontal cortex and dorsolateral prefrontal cortex, which are associated with processes incorporating planning, decision making, cognitive flexibility and working memory.
“These are regions that have a relatively high density of (cannabinoid) receptors-and thus could be affected by heavy weed use,” say the researchers.
Short-Term Cognitive Impacts
The study also revealed that, acutely, cannabis use during that session was linked with diminished performance and reduced frontal activation during working memory tests. However, the associations were not statistically significant.
“The association we observed between recent use and working memory task activation and performance suggests that abstaining from cannabis prior to cognitively demanding situations will likely help with performance,” researchers stated.
“The exact duration of this period of abstinence is unclear, but studies suggest that residual cognitive effects of cannabis may remain for 2 to 4 weeks after abstinence,” they continued.
Researchers stated that larger studies are required to monitor the impact of cannabis consumption on brain function, as reported by HealthDay.
In the meantime, “our findings highlight the need to educate cannabis users about the consequences of recent and heavy lifetime cannabis use on cognitively demanding working memory tasks,” they concluded.