UK Biobank Study Finds Past Cannabis Use Linked to Better Cognitive Performance in Older Adults

Cross-sectionally, lifetime cannabis users (17% of sample) performed better in attention (B=0.071), executive function (B=0.047), processing speed (B=0.363), visual memory (B=0.062), and working memory (B=0.181). Current use associated with better working memory (B=0.169). Longitudinally, past use linked to less decline in executive function, but longer duration predicted steeper processing speed decline.

Cross-sectional (n=67,713) and longitudinal (n=52,002) analyses of UK Biobank participants aged 60+. Self-reported cannabis use patterns. Computerized cognitive tests for attention, executive function, processing speed, visual and working memory. Multivariable linear regression adjusted for demographics, health, and lifestyle.

This is one of the largest studies examining cannabis and cognition in older adults. The finding that past use is associated with better cognitive performance challenges assumptions about long-term cognitive harm, though the relationship is complex.

The complex pattern — better cross-sectional performance but domain-specific longitudinal decline with heavy use — suggests cannabis effects on cognition are nuanced. Survivor bias and confounding (e.g., education, personality traits correlating with both cannabis use and cognitive performance) may explain some findings.

Self-reported cannabis use subject to recall bias. UK Biobank participants are healthier and more educated than the general population (healthy volunteer bias). Cross-sectional associations cannot determine causation. Confounders like personality traits may drive both cannabis use and cognitive performance.