Chronic cannabis use impairs the brain's ability to learn motor skills

This study examined how chronic cannabis use affects motor learning and brain activity in 30 regular cannabis users compared to 32 non-users. Researchers used specialized tests to measure how well participants could learn movement sequences automatically (without conscious effort) and assessed their memory and brain activity patterns. Despite showing some motor learning ability overall, cannabis users with longer histories of use showed significantly weaker learning of motor sequences and performed worse on memory tasks. The findings reveal that chronic cannabis use may impair the brain systems responsible for learning complex movements—skills essential for everyday activities like typing, playing sports, or dancing.

The research discovered that chronic cannabis users exhibited abnormally high electrical activity in their brains at rest, particularly in beta and gamma frequency bands, which the researchers describe as creating "cortical noise" that interferes with normal brain function. This increased background brain activity appears to disrupt the corticostriatal pathways—neural circuits crucial for automatic motor learning and movement coordination. Additionally, the cannabis group performed significantly worse on visuospatial memory tests in both forward and backward sequences, suggesting broader impacts on cognitive systems beyond just motor learning.

These findings have important implications for regular cannabis users, suggesting that prolonged use may compromise the brain's ability to learn and execute complex motor skills automatically. This could affect everything from fine motor precision to coordination. The study also indicates that cannabis's effects on the motor system may be more extensive than previously understood, potentially affecting neural pathways that support learning and skill development. While the research doesn't determine whether these effects are reversible with abstinence, it highlights an understudied area of cannabis neuroscience relevant to users of all ages.