Heavy Cannabis Use May Lower Brain Activation on Working Memory Task

Anterior insula, medial prefrontal cortex, and dorsolateral prefrontal cortex associated with history of heavy use

By Elana Gotkine HealthDay Reporter

TUESDAY, Feb. 4, 2025 (HealthDay News) — Lifetime history of heavy cannabis use is associated with lower brain activation on working memory tasks among young adults, according to a study published online Jan. 28 in JAMA Network Open.

Joshua L. Gowin, Ph.D., from the University of Colorado Anschutz Medical Campus in Aurora, and colleagues examined the association of lifetime history of heavy cannabis use and recent cannabis use with brain activation across a range of brain functions in a cross-sectional study using data for young adults (aged 22 to 36 years). Brain activation was examined during each of seven tasks administered during the functional magnetic resonance imaging session.

The study included 1,003 participants: 8.8, 17.8, and 73.4 percent were classified as heavy users, moderate users, and nonusers, respectively. The researchers observed an association between heavy lifetime use and lower activation on the working memory task. The anterior insula, medial prefrontal cortex, and dorsolateral prefrontal cortex were regions associated with a history of heavy use. Associations were seen for recent cannabis use with poorer performance and lower brain activation in the working memory and motor tasks; the associations did not persist after false discovery rate correction. No associations were seen for other tasks and lifetime history of heavy use, recent use, or dependence diagnosis.

“These findings suggest that large, longitudinal studies are needed to assess the causality of cannabis use toward altering brain function and the duration over which these effects persist,” the authors write.