2024-11-08 16:00:00
According to a new study led by Graciela Pineyro and Tomas Paus, two researchers at CHU Sainte-Justine in Montreal (Canada), cannabis use during adolescence can lead to thinning of the cerebral cortex. This is the outer layer of the brain, made up of a set of folds (convolutions). The two hemispheres each have four lobes (frontal, parietal, temporal, occipital), which perform specific functions. These encompass cognitive abilities, such as thinking, language, memory, reasoning, and decision-making. The cortex is also involved in sensory perception (such as sight, hearing, touch) and voluntary motor control.
THC directly impacts neurons
The study demonstrates that THC (tetrahydrocannabinol), the main active compound in cannabis, causes a reduction in the arborization of dendrites, this “antenna network” in the extension of neurons, essential for communication between them. Consequence: this phenomenon leads to atrophy of certain regions of the cerebral cortex, a problem at an age when the brain is fully maturing. The researchers reached this conclusion by combining two complementary approaches, one in mice and the other in a group of adolescents.
« Comparing the brain to a computer, neurons would be the central processor, receiving all information through synapses (connections, editor’s note) via the dendritic network », Explains Tomas Paus, professor of psychiatry and neuroscience at the University of Montreal. “ A reduction in the supply of information to the central processor by dendrites makes learning, social interactions and handling new situations more difficult. »
By analyzing magnetic resonance images (MRI) of adolescent brains, these same researchers had already noted that young people who had used cannabis before the age of 16 had a thinner cerebral cortex. But this method could not prove causality or precisely understand the effect of THC on brain cells. This is where the mouse and Graciela Pineyro’s team specializing in molecular biology come in. “This mouse model made it possible to demonstrate that THC modifies the expression of certain genes which influence the structure and function of synapses and dendrites,” she explains. This phenomenon leads to atrophy of the dendritic network, contributing to the thinning observed in certain regions of the cortex.
Source : Navarri X, Robertson DN, Charfi I, et al. Cells and Molecules Underpinning Cannabis-Related Variations in Cortical Thickness during Adolescence. J Neurosci. 2024 Oct 9;44(41):e2256232024
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#visible #effects #structure #adolescent #brain
**Interview with Graciela Pineyro: Understanding the Impacts of Adolescent Cannabis Use on Brain Development**
**Editor:** Today, we have with us Graciela Pineyro, a researcher at CHU Sainte-Justine in Montreal, who recently co-led a significant study on the effects of cannabis use during adolescence. Graciela, thank you for joining us.
**Graciela Pineyro:** Thank you for having me.
**Editor:** Your study found that cannabis use during adolescence can lead to thinning of the cerebral cortex. Can you explain what the cerebral cortex is and why its development is crucial during these formative years?
**Graciela Pineyro:** Absolutely. The cerebral cortex is the outer layer of the brain and is responsible for many critical functions, including cognition, sensory perception, and voluntary motor control. During adolescence, the brain undergoes significant development, and changes in the cortex can impact cognitive abilities such as thinking, reasoning, and decision-making, which are essential for functioning in everyday life.
**Editor:** You mentioned that THC, the main active compound in cannabis, impacts neuron structure. What exactly happens to neurons in the presence of THC?
**Graciela Pineyro:** Our research indicates that THC reduces the arborization of dendrites, which are the extensions of neurons that help communicate signals between them. This dendritic network is vital for processing information and learning. When dendrites are less branched, it can impair neuronal communication and potentially affect cognitive functions.
**Editor:** Considering the implications of your findings, what recommendations would you give to parents and adolescents regarding cannabis use?
**Graciela Pineyro:** It’s important for parents to engage in open conversations with their children about the risks associated with cannabis, particularly during teenage years when brain development is critical. Educating adolescents on the potential effects of cannabis on their cognitive functions might help them make more informed decisions.
**Editor:** What are the next steps for your research team in studying the long-term effects of THC on brain development?
**Graciela Pineyro:** Our team plans to continue this line of research by exploring the long-term impacts of adolescent cannabis use on cognitive abilities in adulthood. We want to assess whether the changes observed during adolescence persist and how they affect individuals in their later years.
**Editor:** Thank you, Graciela, for shedding light on this important topic. Your work is crucial in understanding the relationship between cannabis and brain development during adolescence.
**Graciela Pineyro:** Thank you for the opportunity to discuss our findings.
