Friday, March 1, 2024

Cannabis Use in Adolescence: What are the Neurologic Effects?

 In current days especially with the legalization of cannabis in more and more states, there is increased accessibility to cannabis, and the cannabis on the market today has higher levels of THC than ever seen before. This is the first generation of youth that has this accessibility to cannabis and synthetic cannabis which has caused cannabis use to increase by 245% in teens over the past 20 years. Additionally, 78% of first-time cannabis users are between the ages of 12 and 20 years old. As a result of this new accessibility and increased use of cannabis by teens, the long-term neurological effects are still relatively unknown. 

Cannabis works in that the active ingredient (THC) binds to cannabinoid receptors which is what causes the reward, pleasure, and hunger effects of using cannabis. This is relatively un-problematic in adult brains, but what about in adolescent brains that are still developing? Cannabis use in adolescence can alter cortical regions rich in cannabinoid-1(CB1) receptors. Specifically during the time of adolescence, the brain has a heightened sensitivity to disruptions in the endocannabinoid system. Disrupting the endocannabinoid system can have many implications but most commonly negative effects on neurodevelopment and behavior. 

In the investigation Association of Cannabis Use During Adolescence With Neurodevelopment, a series of experiments was done that evaluated the effects of continuous cannabis exposure in humans and mice. In the human analysis researchers looked at a group of 14-year-olds who were chronic cannabis users and took fMRI and PET scans of all of the subjects. They then conducted the same tests on the same group of subjects when they were 19. The magnetic resonance imaging revealed accelerated age-related cortical thinning over the 5 years. Another thing the experiment looked at was the difference in the number of CB1 receptors between the start and end of the five years. PET scans showed that CB1 receptor availability was much lower after 5 years and those same subjects displayed attention impulsiveness (inability to pay attention or concentrate). In another experiment with rats, repeated exposure to THC in adolescent rats decreases social behaviors and alters motivational processes in adult rats. They discovered that in particular cannabinoids appear to have effects on short-term working memory which was shown through a series of maze experiments. Concerning the control rats, the rats who were administered regular cannabis for an extended period displayed difficulty making it through mazes and completing matching tests. This means their short-term working memory was impaired as a result of the chronic cannabis exposure. 

The results of the human analysis and rat experiments involving chronic cannabis use clearly show a direct correlation with working memory, attention, and cortical thinning. This is something that needs to be taken into great consideration when we look at how high the levels of THC in strains of cannabis are and how many teens are regular cannabis users. This needs to be continually researched and studied because the true impact of adolescent cannabis use in adulthood won't be seen until this population of teens and young adults is older. 





References 

Albaugh MD, Ottino-Gonzalez J, Sidwell A, et al. Association of Cannabis Use During Adolescence With Neurodevelopment. JAMA Psychiatry. 2021;78(9):1031–1040. doi:10.1001/jamapsychiatry.2021.1258


Lubman DI, Cheetham A, Yücel M. Cannabis and adolescent brain development. Pharmacol Ther. 2015;148:1-16.


Rubino  T, Vigano’  D, Realini  N,  et al.  Chronic delta 9-tetrahydrocannabinol during adolescence provokes sex-dependent changes in the emotional profile in adult rats: behavioral and biochemical correlates.   Neuropsychopharmacology. 2008;33(11):2760-2771. doi:10.1038/sj.npp.1301664


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