Moderate cannabis use linked to preserved brain health in older adults
A UK Biobank study of 26,000+ adults aged 40–77 found lifetime cannabis use generally associates with larger volumes in CB1-rich brain regions (notably the hippocampus) and better cognitive performance, with the strongest benefits in moderate users; however, some regions showed different effects (posterior cingulate volume lower), and researchers caution that potency, usage patterns, and aging context matter, so this is not a clinical recommendation.