Researchers say cannabis use may be linked to brain benefits in older adults.

A UK study of 26,362 adults ages 40 to 77 found that cannabis use was generally associated with larger brain volumes in several regions and with somewhat better performance on cognitive tests. The research team says the results are nuanced and that further study is underway.

A new UK study reports links between cannabis use and measures of brain structure and cognition in middle-aged and older adults. Researchers analyzed MRI scans and cognitive tests from 26,362 participants aged 40 to 77 to investigate regions rich in CB1 cannabinoid receptors. Interest in this question has grown as cannabis use has increased among older Americans and prior research focused mainly on adolescents. The lead author described the findings as unexpected and emphasized complexity in how cannabis may affect the aging brain. Key findings: - The study sample included 26,362 adults in the UK with an average age of 55 who completed questionnaires, brain MRIs, and cognitive tests. - Cannabis use was generally associated with larger volumes in several brain regions, and users tended to perform better on multiple cognitive measures linked to learning, memory, processing speed, attention and executive function. - Moderate cannabis users most often showed the largest brain volumes and better cognitive performance across affected measures. - Some measures differed: heavy users showed stronger results for right amygdala volume and visual memory and learning in this sample. - Higher cannabis use was linked to lower volume in the posterior cingulate, a region involved in memory and emotional processing, an effect the authors noted is not straightforward to interpret. - The authors noted limits in detailed use-pattern data and said additional analyses of brain function are under review. Summary: The study presents nuanced associations between cannabis use and brain structure and cognition in middle-aged and older adults rather than a simple benefit-or-harm conclusion. Researchers emphasize that effects appear to vary by dose, brain region and cognitive test, and they report further work on brain function in the same cohort is under review.