Teen Cannabis Use Linked To Brain Thinning

A groundbreaking study [1] published in the Journal of Neuroscience has revealed alarming evidence linking cannabis use to brain thinning in adolescents. The research, conducted by a team of scientists from the University of Montreal, combines both animal and human studies to provide a comprehensive look at how marijuana affects the developing brain.

Dr. Tomáš Paus, lead researcher and professor of psychiatry and addictology, explained, “We’ve uncovered a potential mechanism for how cannabis use during adolescence might alter brain structure.” The study found that THC, the primary psychoactive component in cannabis, causes a reduction in the branching of neurons, which are crucial for communication between brain cells.

Paus explained that in humans, a decrease in input from the affected dendrites “makes it harder for the brain to learn new things, interact with people, cope with new situations, et cetera. In other words, it makes the brain more vulnerable to everything that can happen in a young person’s life.”

In a series of experiments on mice, researchers observed that exposure to THC led to a decrease in dendritic branches and spine numbers in the frontal cortex. Dr. Graciela Piñeyro, a co-author of the study, noted, “What surprised me was finding that THC in the mice was targeting the same type of cells and structures that Dr. Paus had predicted would be affected from the human studies.”

The human component of the research involved MRI scans of 467 male adolescents, revealing differences in cortical thickness between cannabis users and non-users across multiple brain regions. Strikingly, the genes affected in the mouse experiments were also found to be altered in the human subjects who had used cannabis.

Dr. Yasmin Hurd, an independent expert from the Icahn School of Medicine at Mount Sinai, commented on the study’s implications: “The results emphasize that consumption of potent cannabis products during adolescence can impact cortical function, which has significant implications for decision-making and risky behavior as well. It also can increase vulnerability to psychiatric disorders such as schizophrenia.”

The findings have raised concerns among medical professionals about the potential long-term effects of adolescent cannabis use. Dr. Ronald Ellis from the University of California, San Diego, advised, “Clinicians should discuss cannabis use history carefully and confidentially with adolescent patients to better provide advice on its potential risks.”

This research highlights the need for caution because of the effects of marijuana on the developing brain. Dr. Paus concluded: “If you’re going to use cannabis, don’t start early. If you have to, then do so in moderation. And if you have family history of mental illness, be very careful.”

This study signals a strong call for caution, especially for young users with genetic risks [2].

References

1. Navarri, Xavier, et al. “Cells and Molecules Underpinning Cannabis-Related Variations in Cortical Thickness during Adolescence.” 9 Oct 2024.

2. Larkin, Marilynn. “Cannabis Use Linked to Brain Thinning in Adolescents.” Medscape Medical News, 4 Nov 2024.