Long-Term Neurobiological Consequences of Adolescent Cannabis Exposure: Evidence from Animal Models and Implications for Nigerian Youth Drug Policy

Background: Adolescent cannabis use is rising globally, including in Nigeria where prevalence among secondary and tertiary students is estimated to exceed 10 percent. The adolescent brain, undergoing critical synaptic pruning and myelination, is uniquely vulnerable to the endocannabinoid-disrupting effects of tetrahydrocannabinol (THC). This study characterises the long-term neurobiological consequences of adolescent THC exposure using rodent models and critically appraises implications for Nigerian youth drug policy. Methods: Male and female Wistar rats received escalating doses of THC (2.5 to 10 mg/kg i.p.) or vehicle during postnatal days 35 to 55, representing the adolescent window. Long-term behavioural outcomes (anxiety, cognition, social behaviour, and prepulse inhibition) were assessed in adulthood (postnatal days 90 to 120). Neurobiological endpoints included prefrontal cortex dopaminergic signalling, hippocampal dendritic spine density, and CB1 receptor expression measured by Western blot and immunofluorescence. Results: Adolescent THC-exposed animals showed persistent deficits in working memory and prepulse inhibition, increased anxiety-like behaviour, and reduced prefrontal dopamine D2 receptor expression in adulthood. Hippocampal dendritic spine density was significantly reduced. Female animals showed greater vulnerability on cognitive indices. Conclusion: Adolescent THC exposure produces lasting neurobiological alterations in rodents with translational relevance to human adolescent cannabis use. These findings provide pharmacological evidence to inform age-specific cannabis regulation and prevention policy in Nigeria. Keywords: cannabis, THC, adolescent brain, neurotoxicity, drug policy