Marijuana and Brain Development: What You Should Know 

Marijuana and Brain Development: What You Should Know 

Marijuana is the most commonly misused drug in the United States, with 17.9% of Americans aged 12 and up indicating that they had used it within the past year, as of 2020. Among adolescents aged 12-17, 10.1% used marijuana in 2020. The public tends to have pretty accepting attitudes toward marijuana use, as just 27.4% of people perceive that smoking marijuana once or twice per week comes with significant risk. While marijuana use is common and generally accepted, that doesn’t mean it is without consequences. One of the greatest risks associated with marijuana misuse for youth is impaired brain development. In some cases, individual or group therapy can help youth understand the risks associated with marijuana use, and discover alternative coping methods.  Learn the dangers below. 

The Vulnerability of the Developing Brain 

One factor to consider when evaluating marijuana and brain development is the fact that teens are likely to be at greater risk of negative consequences from marijuana use when compared to adults. Teenagers undergo a significant amount of brain development and are particularly vulnerable to the adverse effects of drugs. Given this fact, it is not surprising that studies have shown that adolescent marijuana use causes changes in brain activity and can make cognitive performance less efficient. There is also evidence that teenage marijuana use causes more impairment in cognitive functioning when compared to marijuana use that begins during adulthood. 

Marijuana and the Structure of the Developing Brain

Marijuana use is detrimental to brain development because of the changes that occur during the teenage years. During this time, the adolescent brain undergoes a process called pruning, in which brain connections that are not used are removed. The brain also becomes more efficient at sending messages via nerve cells.


At the same time, brain areas involved in emotions and risk-taking mature during adolescence, whereas the prefrontal cortex, which is responsible for rational decision-making, is not yet mature and continues to develop through young adulthood. The imbalance between the emotional and rational areas of the brain is responsible for stereotypical teenage behavior, such as impulsive decision-making. As the brain develops through the adolescent years and into young adulthood, this imbalance corrects itself. 


When marijuana is added to the equation, the processes above are disrupted. One area of the brain negatively affected by teenage marijuana use is the anterior cingulate cortex (ACC), a region responsible for self-regulation. Research has shown that over time, teens who do not use marijuana show increases in connectivity, which is an indicator of overall brain functioning, in the ACC. In contrast, teenage marijuana users experience decreased functional connectivity in the ACC as time progresses, which impairs executive functioning skills, such as impulse control, time management, and organization. 

Marijuana Use and Overall Intellectual Functioning

Not only does teen marijuana use interfere with the development of rational decision making abilities; it can also negatively impact overall cognitive functioning and reduce intellectual abilities. High-quality evidence from seven studies comparing teen marijuana users to non-users found that heavy marijuana use and addiction during adolescence decreases intellectual functioning and reduces overall IQ by an average of 2 points. 


This finding adds to a growing body of earlier research which has found that marijuana has a toxic effect on the developing brain. Studies have also shown that ongoing marijuana use is linked to declines in several areas of brain functioning from childhood to adulthood, leading to various cognitive problems. 


Based on available evidence, marijuana use is not harmless, especially for the developing teenage brain. Adolescents are in a period of critical brain development, and drugs like marijuana can interfere with processes that allow the brain to mature and develop adult-level thinking abilities. The good news, though, is that treatment is available to help teens who are struggling with marijuana use. Through individual and group counseling, teens can learn about the risks of marijuana and develop healthier ways of coping, without turning to substance misuse. 









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