CANNABIS use may leave lasting neurological effects, with new research showing cannabis exposure is linked to reduced brain activation during working memory tasks, suggesting both recent and lifetime cannabis use could influence cognitive function in young adults.
Rising Cannabis Use and Brain Health
Researchers investigated cannabis to determine whether cumulative or recent exposure alters brain activation across cognitive domains. Working memory is particularly important because it supports reasoning, decision making, and learning. Changes in activation may signal altered neural efficiency. Understanding how cannabis affects brain function could clarify potential risks, especially in young adults whose brains are still adapting functionally.
Cannabis and Brain Activation Patterns
This cross-sectional study included 1003 adults aged 22 to 36 years who underwent functional MRI and provided detailed cannabis histories using the Semi-Structured Assessment for the Genetics of Alcoholism, with variables for lifetime history and diagnosis of cannabis dependence. Individuals were categorised as heavy lifetime cannabis users if they had greater than 1000 uses, as moderate users if they had 10 to 999 uses, and as nonusers if they had fewer than 10 uses.
In this study, 88 participants (8.8%) were classified as heavy cannabis users, 179 (17.8%) as moderate users, and 736 (73.4%) as nonusers. Heavy lifetime cannabis use was associated with lower working memory activation, with Cohen d = −0.28 95% CI, −0.50 to −0.06; false discovery rate corrected P = .02. Affected regions included the anterior insula and dorsolateral prefrontal cortex. Recent cannabis use showed poorer activation, but these associations did not remain significant after statistical correction.
Clinical Implications
These findings suggest cannabis exposure may produce measurable and potentially lasting changes in brain function. Reduced activation in working memory regions may influence learning capacity, attention, and executive performance. Notably, cannabis dependence diagnosis alone was not linked to activation differences, suggesting cumulative exposure may be more relevant than diagnostic labels. Future longitudinal studies are needed to determine whether these effects are reversible and how long they persist. Improved understanding could support clinical recommendations and inform public health strategies on cannabis and cognitive wellbeing.
Reference
Gowin JL et al. brain function outcomes of recent and lifetime cannabis use. JAMA Netw Open. 2025;8(1):e2457069.
