Heavy use of cannabis could affect a human’s working memory, which is how the brain retains and uses just-learnt information to perform tasks, according to a new study.
Working memory helps a person follow instructions they’ve just been given or to mentally visualise and manipulate information, like solving a math problem.
Researchers, including those from the University of Colorado, US, analysed the effects of cannabis use in more than 1,000 young adults aged 22 to 36. MRI brain scans of the participants were taken while they performed tasks that tested working memory, reward, emotion, among other cognitive functions.
The study, published in The Journal of the American Medical Association (JAMA) Network Open, found that cannabis had a significant effect on brain function during working memory tasks, and a less significant one while performing other tasks.
“In this study of young adults, lifetime history of heavy cannabis use was associated with lower brain activation during a working memory task,” the authors wrote.
“As cannabis use continues to grow globally, studying its effects on human health has become increasingly important. By doing so, we can provide a well-rounded understanding of both the benefits and risks of cannabis use, empowering people to make informed decisions and fully comprehend the potential consequences,” first author Joshua Gowin, an assistant professor of radiology at the University of Colorado, said.
For the study, young adults who had used cannabis more than 1000 times were considered ‘heavy users’. In the study group, 88 were classified as heavy cannabis users, 179 as moderate and 736 as non-users.
While performing working memory tasks, heavy users of cannabis showed a reduced activity in brain regions involved in important cognitive functions, such as decision-making, memory, attention and emotional processing, the researchers said.
“These findings identify negative outcomes associated with heavy lifetime cannabis use and working memory in healthy young adults that may be long lasting,” they wrote.
