A large new study has found that heavy cannabis use is linked to lower brain activity during tasks that involve working memory. The research, published in JAMA Network Open, analyzed brain scans of over 1,000 young adults aged 22 to 36, making it the largest study of its kind.
The findings showed that 63% of heavy lifetime cannabis users had reduced brain activity when performing a working memory task, compared to 68% of recent users who showed similar effects.
This decline in brain activity was linked to worse performance on memory-based tasks, which could impact daily activities like following instructions, solving problems, or making decisions.
How the Study Was Conducted
The study, led by Dr. Joshua Gowin from the University of Colorado Anschutz Medical Campus, examined how cannabis affects brain function using MRI scans. Participants were categorized based on their cannabis use:
- Heavy users had used cannabis more than 1,000 times in their lifetime.
- Moderate users had used it 10 to 999 times.
- Non-users had used it fewer than 10 times.
Researchers tested seven cognitive functions, including working memory, language, emotional processing, and motor skills. However, the most significant effect of cannabis use was seen in working memory tasks, where brain activity was lower in regions associated with decision-making, memory, and attention.
Key Findings
- Statistically significant impact on working memory: Brain scans revealed that heavy cannabis users had reduced activity in critical brain areas, including the dorsolateral prefrontal cortex, dorsomedial prefrontal cortex, and anterior insula—regions involved in memory, attention, and emotional processing.
- Memory performance declines: The decrease in brain activity was associated with worse performance on working memory tasks.
- Other cognitive functions less affected: While some tasks suggested possible cognitive impairment, only working memory showed a statistically significant decline after rigorous analysis.
What This Means for Cannabis Users
Dr. Gowin highlights that as cannabis use grows worldwide, understanding its effects on the brain is crucial for informed decision-making. While cannabis has potential therapeutic benefits, this study suggests it may negatively impact cognitive function, especially in heavy users.
One important takeaway is that abstaining from cannabis before cognitive tasks could help improve performance. However, for heavy users, quitting suddenly may also temporarily affect cognition. Dr. Gowin emphasizes that more research is needed to determine how long these effects last and whether cannabis causes long-term brain changes.
Next Steps in Research
The study raises important questions about how cannabis affects brain function over time. Researchers now aim to conduct long-term studies to determine:
- Whether cannabis permanently alters brain function.
- How long cognitive effects persist after stopping use.
- Whether the impact differs across age groups and levels of use.
For now, the study suggests that heavy cannabis users should be mindful of potential cognitive effects, particularly when engaging in activities that require strong working memory and concentration.
If you care about dementia, please read studies about dietary strategies to ward off dementia, and how omega-3 fatty acids fuel your mind.
For more health information, please see recent studies about Choline deficiency linked to Alzheimer’s disease, and what to eat (and avoid) for dementia prevention.
The research findings can be found in JAMA Network Open.
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