Cannabis legalization has many parents and researchers worried about the long-term implications of chronic marijuana use among adolescents. Cannabis use has become more accessible and accepted, leading some people to believe that teens will be lighting up joints at an increasingly alarming rate. Research into pot use among teens is growing, but there are major inconsistencies between study results.
Some studies show that cannabis use in teens can affect cognitive abilities later in life. Other studies find that cannabis use doesn’t lead to any significant structural changes in adolescent brains. Experts recommend teens to err on the side of caution when consuming cannabis products.
Cannabis Use Among Teens
As recreational marijuana use continues to rise in legal states, preventing cannabis use among youth is a top priority for lawmakers. A recent paper shows that states that legalized recreational marijuana had an eight percent decrease in the number of high schoolers who had used marijuana in the last 30 days. Additionally, there was a nine percent drop in the number of students who said they’d used marijuana at least 10 times in the last 30 days.
Research shows that cannabis legalization is not correlated with marijuana use among adolescents. That’s not to say that adolescents aren’t smoking weed. A study published in the Journal of Adolescent Health found that teens that had a job were more likely to consume cannabis than nonworking adolescents. Some of the study’s major findings include:
- Teens working in retail and service sectors were more likely to use cannabis than nonworking teens or teens who work in informal settings
- Between 2010 and 2016, pot use decreased significantly among working and nonworking teens
- Marijuana use by working 12th graders increased
The Adolescent Brain
Even the smartest adolescents haven’t fully developed the part of their brain involved with making sound decisions. Researchers say that an adolescent’s brain isn’t fully developed until they’re 25. In particular, a teen’s prefrontal cortex isn’t as developed as an adult’s. Adults use this part of the brain to make rational decisions. Teens process information in the amygdala, the part of the brain that dictates our emotions and behavior.
The body’s endocannabinoid system regulates appetite, emotion, sleep, memory, and movement. This network of cell receptors found throughout the body develops significantly during adolescence. In addition, a teen’s limbic system, which is the brain’s reward pathway, is growing faster than the prefrontal cortex. The imbalance of systems has been shown to be negatively affected by early marijuana use.
Cannabis Effects on Teen Brains
Studies on the brains of adolescents who use cannabis are inconsistent, contradictory, and littered with many testing limitations. Although a lot of the research suggests that early cannabis use can lead to issues with brain functioning, even if the structure remains largely the same, not all research agrees.
A study published in May 2019 in the journal Addictive Behaviors found that marijuana use made teens more susceptible to mood liability, or rapid fluctuations in emotional states. Researchers studied 466 adolescents and found that females were higher in anxious mood liability than males, but there were no anxious mood liability differences in gender among teens who consumed marijuana.
A 2016 review published in Biological Psychiatry showed that “regular cannabis users show abnormalities within brain regions that are high in cannabinoid type 1 receptors, particularly the hippocampus and the [prefrontal cortex].” Researchers believe THC is the culprit for the neural damage and CBD is a protective compound, but they acknowledge that more research must be done.
A 2019 study from the University of Oxford performed a systematic review and meta-analysis of 23,317 individuals from across the world to find out if cannabis use in teens increases depression, anxiety, and suicidality. Researchers concluded that “adolescent cannabis consumption was associated with increased risk of developing depression and suicidal behavior later in life, even in the absence of a premorbid condition. There was no association with anxiety.”
While some research suggests that cannabis use is linked with structural changes in the brain, other studies have shown that there are no significant differences in structure between daily users and nonusers. The changes to gray matter, cortical thickness, and volume that have been found can also be vulnerable to other environmental factors that can influence substance abuse.
The small amount of research and sample sizes also makes it difficult to come to an agreement on the long-term effects of cannabis use in teens. Furthermore, each study has different definitions of cannabis use disorder, study parameters, and definitions for low and high-consumption users. For now, the research on teen cannabis use does indicate some abnormalities in brain function in later life.
While the jury’s still out on the effects of cannabis on adolescent brains, parents and teens should be aware of the potential short- and long-term effects marijuana can have on their brain. Medical cannabis can relieve many medical symptoms, but it’s also important to know that cannabis affects everyone differently. As more research trickles in, parents and teens can become better informed when discussing cannabis use.