This is severe cannabis abuse and doesn’t apply for the small doses we’re thinking of
Lifetime Cannabis Use Is Associated with Brain Volume and Cognitive Function in Middle-Aged and Older Adults
Results:
Lifetime cannabis use was positively associated with regional brain volume in CB1-rich regions, including the caudate, putamen, hippocampus, and amygdala. Greater lifetime use was also linked to better performance in learning, processing speed, and short-term memory. Individuals reporting use limited to adolescence also showed larger regional volumes and better cognitive performance than non-users. Sex differences in cannabis effects on brain volume and cognition were also observed.
Conclusions:
Results highlight that cannabis may influence brain health differently across the lifespan, potentially offering protective effects in older age while posing risks earlier in development. Protective effects may result from endocannabinoid-mediated modulation of inflammation, immune function, and neurodegeneration. Observed sex differences likely reflect variation in the endocannabinoid system and underscore the importance of considering sex as a biological variable in studies of cannabis and brain health.
https://www.jsad.com/doi/epdf/10.15288/jsad.25-00346?role=tab