Cannabis Effects on Cognition Depend Heavily on Age: Harmful for Young Brains, Possibly Helpful in Old Age

Prenatal and adolescent cannabinoid exposure consistently led to long-term cognitive deficits in animal models, while exposure in aged animals showed potential beneficial effects on cognition. The role of dosage was difficult to establish clearly, especially during adolescence, though emerging evidence suggests dose may matter more at other life stages.

Systematic scoping review of PubMed from 2015 to December 2021. Included studies examining effects of natural or synthetic cannabinoids on cognitive performance in animal models where exposure occurred prenatally, during adolescence, or in older animals.

Different age groups are using cannabis at increasing rates, from pregnant women to elderly patients seeking medical cannabis. Understanding that the same substance may be harmful during development but potentially beneficial in old age has major implications for policy and clinical guidance.

This age-dependent pattern aligns with what we know about the endocannabinoid system's role in brain development versus maintenance. During development, cannabis may disrupt critical neural processes, while in aging brains, it may compensate for declining endocannabinoid function.

Animal studies have limited translatability to humans. The review focused on cannabinoid exposure broadly, including synthetic cannabinoids that differ from what humans typically use. Publication bias may favor significant findings. Dose-response relationships remain poorly characterized.