CHICAGO — As marijuana continues to be decriminalized across the United States, the dangers of children obtaining and using the drug are also coming into light. Now, a recent study shows how adolescent cannabis use could change the way neurons function in certain areas of teens’ brains, specifically the regions behind decision-making, planning, and self-control.
The study, conducted by University of Illinois at Chicago psychologists, used an animal model of the structural development of the prefrontal cortex (PFC), which controls all high-level cognitive functions.
Within the pre-frontal cortex, there is a support structure called the perineuronal net, which forms a type of protective shield using proteins around inhibitory cells. This helps secure the cells’ connections with excitatory neurons and regulate overall PFC activity. Scientists know that perineuronal net formation can be influenced by narcotic use, but the specific effects of marijuana are not yet known.
So, in order to investigate how adolescent cannabis use impacts perineuronal nets in the PFC, researchers gave adolescent rats a synthetic cannabinoid substance similar to the main psychoactive ingredient in cannabis, THC. The rats were administered this substance for either one day, ten days, or ten days followed by a period of abstinence. Then, the perineuronal net structures in these rats were compared to other animals who hadn’t received any synthetic THC.
Rats that were exposed to the synthetic cannabinoid exhibited reduced development around inhibitory cells during adolescence. The researchers also found that this reduction was more prominent among male rats.
“Our evidence suggests that exposure to cannabinoids during adolescence alters brain maturation in the prefrontal cortex,” says study leader Eliza Jacobs-Brichford in a university release. “These results may offer a mechanistic explanation for functional and behavioral changes caused by adolescent cannabinoid exposure.”
“Adolescence is a crucial time for fine-tuning the balance of excitatory and inhibitory neurons in the brain, which combine to control precise patterns of brain activity,” adds co-author Jamie Roitman, a UIC associate professor of psychology. “Substance use as a teenager thus has the potential to disrupt the normal developmental trajectory of the PFC, with potentially long-term consequences for decision-making.”
The findings were presented at the annual meeting of the Society for Neuroscience in 2018.