Study Looks into Effects of Both Recent and Lifetime Cannabis Use on Brain Function

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A recent study published in JAMA, looked to investigate how recent and lifetime cannabis use affected brain function during cognitive tasks (1). Researchers organized a cross-sectional study consisting of 1,003 young adults between the ages of 22-36 years old. Data was collected via urine toxicology, magnetic resonance imaging (MRI), as well as cannabis use data. The information was gathered and then analyzed from January 31 to July 30, 2024 (1).

To define heavy cannabis use, researchers sifted participants through the Semi-Structured Assessment for the Genetics of Alcoholism to help place them into specific groups. For individuals that had more than 1,000 reported uses of cannabis, they were placed as heavy lifetime cannabis users. Moderate users were categorized if they had 10 go 999 cannabis uses and individuals that had less than 10 users were labeled as nonusers (1). To decipher recent use, participants were required to submit urine samples on the day of scanning.

Researchers analyzed brain function through seven tasks that were administered during the “functional MRI session” (1). This included emotion, working memory, language, reward, relational assessment, theory of mind, and motor. The study mentioned that (1), “Mean activation from regions associated with the primary contrast for each task was used. The primary analysis was a linear mixed-effects regression model (one model per task) examining the association of lifetime cannabis and recent cannabis use on the mean brain activation value.”

Data showed that there was no direct relationship regarding lifetime history of cannabis use and task activation after recent usage was taken into account. Researchers found that (1), “In this study of young adults, lifetime history of heavy cannabis use was associated with lower brain activation during a working memory task. These findings identify negative outcomes associated with heavy lifetime cannabis use and working memory in healthy young adults that may be long lasting.” With the new findings from this study, further research will likely be inspired to dig deeper into the effects the severity of cannabis use has on brain function.

Reference

1. Gowin JL, Ellingson JM, Karoly HC, et al. Brain Function Outcomes of Recent and Lifetime Cannabis Use. JAMA Netw Open. 2025;8(1):e2457069. doi:10.1001/jamanetworkopen.2024.57069