A collaborative research study has revealed how cannabis use impacts brain development in adolescents, particularly leading to a reduction in size in specific areas of the cerebral cortex.
According to a recent study led by Graciela Piñeyro and Tomáš Paus, who are affiliated with CHU Sainte-Justine and teach at the Université de Montréal Faculty of Medicine, cannabis consumption may result in thinning of the cerebral cortex in teenagers. This research involved two laboratories with complementary methods and shows that THC, the active component in cannabis, leads to the shrinkage of dendritic arborization. Dendritic arborization is crucial for neuron communication, functioning as the “network of antennae” for neurons. This shrinkage contributes to the atrophy of certain cerebral cortex areas, which is concerning during a critical brain maturation phase.
“If we visualize the brain as a computer, neurons act as the central processor that receives all information through synapses and the dendritic network,” indicates Tomáš Paus, who also teaches psychiatry and neuroscience at Université de Montréal. “A reduction in data input to the central processor from dendrites hampers the brain’s ability to learn, engage socially, and handle new challenges. This means the brain becomes more susceptible to experiences in a young person’s life.”
A Comprehensive Approach for Greater Insight into Human Impact
This research is distinct due to its multi-level methodology. “By examining MRI scans of a group of teenagers, we previously established that those who used cannabis before age 16 had a thinner cerebral cortex,” remarks Tomáš Paus. “However, utilizing MRI alone does not allow us to establish causality or fully comprehend the effects of THC on brain cells.”
To address MRI’s limitations, Graciela Piñeyro’s team introduced a mouse model. “This model showed that THC alters the expression of certain genes which influence the structure and function of synapses and dendrites,” states Graciela Piñeyro, who is also a professor in the Pharmacology and Physiology Department at Université de Montréal. “This leads to atrophy of the dendritic structure, which may explain the thinning seen in specific cortex regions.”
Interestingly, these genes were also identified in humans, especially in the thinner cortical areas of adolescents who experimented with cannabis. By merging their unique research techniques, the two teams were able to confirm with high confidence that the genes affected by THC in the mouse model were linked to the cortical thinning observed in young people.
With the rise in cannabis use among North American youth and the growing concentrations of THC in commercial cannabis products, it’s crucial to enhance our understanding of how THC impacts brain development and cognitive functions. This fruitful collaborative study, utilizing advanced techniques in cellular and molecular biology, imaging, and bioinformatics, marks a significant advancement towards formulating effective public health strategies.
About the Study
The research article titled “Cells and Molecules Underpinning Cannabis-Related Variations in Cortical Thickness during Adolescence” was authored by Xavier Navarri, Graciela Piñeyro, and Tomáš Paus and was published in the Journal of Neuroscience on October 6, 2024.
