Researchers Track Brain Changes in Unprecedented 1,000-Person Study
A recent study published in JAMA Network Open has found that heavy cannabis use may have lasting impacts on brain function, particularly in the area of working memory. The study, which is one of the largest of its kind, suggests that even after quitting, heavy marijuana use can lead to reduced brain activity during memory tasks.
The research team, led by Joshua Gowin, PhD, from the University of Colorado School of Medicine, analyzed brain scans from 1,003 young adults and found that those who had used cannabis heavily showed less brain activity during memory tasks compared to those who rarely or never used marijuana. This effect was most noticeable in brain regions responsible for working memory, attention, and decision-making.
The study divided participants into three groups based on their lifetime cannabis use: heavy users (over 1,000 times), moderate users (10-999 times), and non-users (fewer than 10 times). Heavy users were more likely to be male, have lower income and education levels, and show recent cannabis use in drug tests.
The researchers found that heavy cannabis use was associated with reduced brain activity in the working memory task, but not in other cognitive tasks such as emotional processing, language, or logical thinking. Additionally, heavy users who had recently used cannabis performed worse on memory and movement tasks, but these effects were not as statistically significant as the long-term impacts on memory.
The study also observed a gender difference, with men showing more pronounced effects on movement-related brain activity while under the influence of cannabis. This adds to growing evidence that marijuana may affect men and women differently.
The researchers suggest that people who use cannabis regularly may benefit from taking breaks before tackling mentally demanding tasks, but warn that suddenly stopping cannabis use could also disrupt thinking abilities. “Heavy users may need to be more cautious,” Gowin said.
The study’s findings have important implications for public health messaging around marijuana use and suggest that users may need to be more aware of the potential long-term effects of heavy cannabis use on brain function.
