Unveiling the Role of Glial Cells
Cannabis and Brain Development
Although extensive research has delved into the impact of cannabis on neurons, the non-neuronal glial cells, crucial for brain function, have remained relatively uncharted territory.
In a groundbreaking study, Professor Atsushi Kamiya and researcher Yuto Hasegawa from Johns Hopkins University have revealed a concerning link between adolescent cannabis exposure and brain development, pointing to microglia, the immune cells within the brain, as a key player.
Rising Cannabis Use and Its Consequences
Cannabis regulations are loosening globally, including in the United States and Canada, leading to an increase in cannabis-related arrests in Japan. Simultaneously, there is a growing number of users, particularly among young people, sparking a pressing societal concern.
Recent reports from the National Institute on Drug Abuse (NIDA) indicate a steady increase in the concentration of D-9-tetrahydrocannabinol (THC), the primary psychoactive component in cannabis, over the past two decades, raising concerns about its impact on cognitive development in young individuals.
The Overlooked Glial Cells
Historically, research on the effects of cannabis on the brain primarily focused on neuronal changes, with limited exploration of non-neuronal glial cells.
Professor Atsushi Kamiya and Yuto Hasegawa have revealed that cannabis exposure during adolescence significantly affects microglia, the brain’s primary immune cells, causing neurodevelopmental and social memory disorders. They published these findings in the electronic version of the British scientific journal Nature Communications on October 25th.
Cannabis and Mental Health
Cannabis use is recognized as a risk factor for the development of mental illnesses, particularly among young users. However, not all cannabis users experience psychotic symptoms, suggesting that genetics may play a role in the impact of cannabis on brain function.
The Study’s Revelations
The study involved the chronic administration of THC during adolescence to normal mice and a mouse model with a genetic predisposition for psychiatric disorders. The results were striking, with the synergistic effect of cannabis exposure and genetic risk leading to a reduction in the number of microglia and morphological changes indicative of activation.
Impact on Cognitive Function
Additionally, adolescent THC exposure in the model mice resulted in decreased excitability of specific neurons in the medial prefrontal cortex, a critical region for cognitive function. Consequently, social memory suffered. Researchers also demonstrated that these neurological and cognitive dysfunctions could be mitigated by selectively eliminating cannabinoid receptor type 1, the receptor for THC present in microglia.
Cannabis and Brain Development
This study underscores the vulnerability of microglia to cannabis during adolescence, a pivotal period for brain development and the onset of mental disorders. The findings shed light on how these immune cells directly influence neuronal development in the context of cannabis use.
The increasing trend of legalizing cannabis for recreational use abroad has created a perception of cannabis as safe and harmless, leading to a surge in young cannabis users. While medical cannabis has proven effective as a treatment, mounting evidence, including this study, suggests that cannabis may have a detrimental impact on brain development during adolescence.