What’s claimed to be the largest study ever carried out on the effects of cannabis on brain function has found negative impacts on working memory.
Working memory is the ability to remember and process a small amount of information while performing a task. An example is making a phone call to a number you’ve just been told.
The University of Colorado study involved more than 1,000 young adults aged 22 to 36 and involved magnetic resonance imaging (MRI) technology, urine toxicology and cannabis use data. The participants were associated with three groups:
- Heavy users – those who used cannabis more than 1000 times over their lifetime.
- Moderate users – consumed cannabis 10 to 999 times.
- Nonuser – less than 10 times.
During working memory tasks, the researchers found heavy cannabis use (i.e cannabis containing THC) appeared to reduce activity in areas of the brain associated with cognitive functions such as decision-making, memory, attention and emotional processing. 63% of heavy lifetime cannabis users demonstrated reduced brain activity during a working memory task, while 68% of recent users also demonstrated a similar impact. Participants provided urine samples the day MRI scanning occurred to assess recent use of THC.
Only the working memory task showed a statistically significant impairment. The impact was less significant for the other tasks which dealt with reward, emotion, language, motor, relational assessment, and theory of mind.
To minimize risk of false positives, false discovery rate (FDR) correction was used. Like most cannabis- related research the next step is …more research.
“There are a lot of questions we still need answers to regarding how cannabis impacts the brain,” said the study’s first author Joshua Gowin, PhD. “Large, long-term studies are needed next to understand whether cannabis use directly changes brain function, how long these effects last and the impact on different age groups.”
The study, titled “Brain Function Outcomes of Recent and Lifetime Cannabis Use” has been published on JAMA Network Open.
On a related note, last year we published an article on a study that suggested adult medicinal cannabis patients do not experience adverse changes in cognitive performance after a year of regular use.
