Additional Coverage:
- The truth about cannabis: Researchers from largest study on its effects on the brain have a warning for young adults (newsbreak.com)
Local researchers have cast further doubt on the idea that cannabis is harmless due to its natural origins. A new study from the University of Colorado Anschutz Medical Campus suggests a link between heavy, long-term cannabis use and impaired working memory in young adults.
This study, considered the largest of its kind, examined over 1,000 participants aged 22 to 36. Researchers used brain imaging to observe brain activity during a working memory task.
Working memory is crucial for short-term information storage, used in activities like problem-solving and reasoning. A significant portion of recent (68%) and lifetime (63%) heavy cannabis users showed decreased brain activity.
Study co-author Dr. Joshua Gowin emphasized the importance of this research, given the increasing prevalence of cannabis use. He highlighted the need to understand both the risks and benefits, allowing individuals to make informed choices.
Participants completed seven cognitive tests, and researchers used fMRI to analyze brain responses. Lifetime cannabis use was categorized as heavy (1,000+ uses or cannabis dependence diagnosis), moderate (10-999 uses), or non-user (less than 10 uses). Recent use was determined via urine samples.
The study found a correlation between heavy lifetime cannabis use and lower brain activation during the working memory task, even after accounting for recent cannabis use. Other factors like alcohol and nicotine use, age of first cannabis use, and demographics did not explain this connection.
Dr. Gowin stressed the study’s rigorous statistical methods.
While other cognitive tests hinted at potential impairment, only the working memory task showed a statistically significant impact. The study also identified specific brain regions affected by heavy cannabis use, all involved in cognitive functions like attention, memory, and decision-making.
Recent cannabis use was also linked to poorer performance and lower brain activity in motor and working memory tasks, but these findings were not as statistically robust. The results reinforce previous studies suggesting that heavy cannabis use alters brain activity, even without recent use. Abstaining before cognitively demanding situations may improve performance.
However, Dr. Gowin cautioned that abruptly stopping cannabis use could also disrupt cognition, especially for heavy users.
The study had some limitations, including difficulty determining the exact timing, dose, and potency of recent cannabis use. Future research is needed to fully understand the long-term effects of cannabis on different age groups.