What New Brain MRI Research Reveals About Cannabis Use and Working Memory Tasks

In a brain magnetic resonance imaging (MRI) study of over 1,000 young adults, researchers found that 63 percent of those who have used cannabis 1,000 or more times have reduced brain activation for working memory tasks.

For the cross-sectional study, recently published in JAMA Network Open, researchers reviewed functional MRI findings, urine toxicology reports and cannabis use data for 1,003 young adults (mean age of 28.7). According to the study, 88 participants were heavy cannabis users (1,000 or more uses of the drug) and 179 participants were moderate users (10 to 999 uses) with the remaining 736 participants described as non-users (less than 10 uses of cannabis).

In a recent interview, lead study author Joshua Gowin, M.D., said heavy lifetime use of cannabis was associated with lower brain activation during the working memory task with a pronounced impact on the anterior insula, medial prefrontal cortex, and dorsolateral prefrontal cortex.

(Editor’s note: For additional content on MRI, click here.)

“The prefrontal cortex is certainly associated with executive function and executive control. … One of the reasons why the prefrontal cortex is activated during the working memory task is because you have to keep track of a lot of things, and it's cognitively demanding. Since we saw lower activation in the cannabis users in (the prefrontal cortex), we suspect that … cannabis users had perhaps less ability to ramp up that brain region during the cognitively demanding working memory task,” noted Dr. Gowin, an assistant professor of radiology at the University of Colorado School of Medicine in Aurora, Colo.

(Editor’s note: For related content, see “Chest CT Study Shows Higher Emphysema Risk from Combination of Marijuana and Cigarette Smoking,” “Hybrid PET/MRI Assessment with Hippocampal Radiomics May Facilitate Early Alzheimer’s Diagnosis” and “A Closer Look at the New Appropriate Use Criteria for Brain PET: An Interview with Phillip Kuo, MD, Part 2.”

For more insights from Dr. Gowin, watch the video below.