Overview
Researchers at the University of Colorado Anschutz Medical Campus analyzed cannabis usage, brain scans, and cognitive test results for over 26,000 adults ages 40-77 using UK Biobank data. Moderate lifetime cannabis users showed larger volumes in brain regions rich in CB1 receptors—areas involved in memory, information processing, and emotion regulation. Users also scored better on cognitive tests measuring learning, processing speed, and executive function. However, higher cannabis use correlated with reduced volume in the posterior cingulate. Researchers caution the observational study cannot prove causation. Experts note this contradicts most prior studies on cannabis and cognition.
Clinical Perspective
THE BRAIN VOLUME STUDY: PROMISING OUTLIER OR PARADIGM SHIFT?
A CU Anschutz study found cannabis users 40-77 showed larger brain volumes and better cognition. 26,000+ adults, UK Biobank data. Moderate users had the most favorable outcomes.
But: it’s observational, can’t prove causation. Higher use reduced posterior cingulate volume. Multiple experts called it an ‘outlier.’ The value isn’t that it proves cannabis is good for brains—it’s that the relationship may differ across the lifespan. What’s harmful for a 15-year-old may not be harmful for a 55-year-old. That hypothesis deserves rigorous testing.
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