The Effects of Alcohol and Marijuana on a Teenager's Brain and Future, by a South Bay Teenager


We thank the clever South Bay mom who assigned her teenage son this  Pass On It research project after he was caught using marijuana. Some really great evidence-based reasons for youth to stave off alcohol and recreational marijuana use until the brain is fully developed, or at least until it's legal. Encourage your teen to share their reasons to say, "I'll pass" to the things that will hold them back, like drugs and alcohol.

Between the ages of 13 and 18, teenagers tend to try many new things. Unfortunately, drugs and alcohol have become increasingly prevalent among those things. Alcohol is the single most used and abused drug by teens in the United States today. In fact, according to the Center for Disease Control and Prevention, people aged 12 to 20 years old drink 11% of all alcohol consumed in the United States. In addition, 90% of that drinking is consumed during binge drinking. On the other hand, Marijuana use by teens accounts for 31% of all drug use when not accounting for alcohol, and National Institute on Drug Abuse’s data states that roughly one in three high schoolers smokes marijuana. Therefore, these two substances (alcohol and marijuana) are a vastly important topic of study, especially the effects they have on teen mental health. The best way to study these substances is to explore research that claims they have negative effects and the research that claims they have little to no effects, and look into the legitimacy and motive of each research agency. I will finish by giving my response to the information I have gained and discuss the possible consequences that alcohol and marijuana use could have on my future education and career.

The sites alcoholthinkagain, muirwoodteens, and samafoundation describe issues with alcohol, marijuana, and both respectively. According to alcoholthinkagain, alcohol disrupts the communication between nerves cells and other cells of the body by damaging neurotransmitters. While these messages in the body are hurt by consuming alcohol, specific areas of the brain are also known to be negatively impacted. For example, the hippocampus, which is responsible for memory and learning, is said to grow to a lesser size than that of a person who does not regularly consume alcohol as an adolescent. The second major part of the brain alcoholthinkagain states is significantly affected by teen alcohol abuse, is the prefrontal lobe. The prefrontal lobe is in charge of planning, judgement, decision making, impulse control, and language. Similar to the hippocampus, the size is reduced by heavy drinking as a teen. When it comes to marijuana, there are other brain-related issues, as described by muirwoodteen’s website. Muirwoodteens states that a study of 18 to 25 year olds showed that there was an abnormally shaped amygdala and nucleus accumbens among the participants who smoked regularly. The amygdala is the center for emotions, emotional behavior, and motivation, and the nucleus accumbens processes rewarding stimuli. Therefore, both of these parts of the brain are very important and damage to either can be harmful, especially when they are still growing. Finally, samfoundation’s website addresses similar ideas to the previous two sites, but also drive home the fact that adolescents are not just less-experienced adults, but they are undergoing an important developmental stage in which that they are prone to errors of judgment, and sensitive to neurological issues caused by psychoactive substances. 

While the majority of research displays how alcohol and drug abuse is especially harmful to developing brains, some research highlights how the effects of marijuana is equal between adults and young adults, and other research even states that marijuana is less harmful than alcohol. A medscape article titled “Teen Marijuana Use Not Harmful?” explores a study conducted by Jordan Bechtold, a psychology researcher at the University of Pittsburgh Medical Center, which tracked 408 boys from adolescence into their mid-30s. The boys were separated into different groups based on marijuana usage and confounding variables such as alcohol and tobacco usage were filtered out. What they found was that the subjects who started smoking in adolescence developed no more physical or mental issues by their mid 30s as the subjects who began smoking in adulthood. Another article by medicalxpress explores two studies, one in the United States and another in the United Kingdom, both which revealed that heavy alcohol use by teens leads to more irregular brain function than heavy marijuana usage. Both of these previous articles serve to diminish the belief in the harmfulness of marijuana, but it is generally agreed upon that teen alcohol use has serious negative effects. In addition, these are only a few studies, and in the context of all substance abuse, cannot be taken as fact.

Regarding those articles that argued for its minimal negative effects, it is important to take into account the goal that each site has for publishing their individual arguments and the legitimacy of their claims. For starters, a follow-up analysis was required for the study talked about in the medscape article. Because of the controversy raised by this study, a new study had to be done by the same group in which the four different test groups were changed to two subgroups: infrequent and nonusers vs. frequent users. What the new study found was pretty much that teens who engaged in frequent marijuana use had a higher probability of meeting criteria for a psychotic disorder than infrequent/nonusers by their 30s. However, because there was not statistical significance between the two groups, this information was not included. Therefore, this further study as a result of controversy shows the illegitimacy of some articles and news sources. It is important to understand that there were harmful effects on those test subjects who used marijuana frequently. The second article I used in paragraph three is also indicative of relatively unreliable information. The apparent goal of this article is to distract from the definitive danger of marijuana by comparing it to another substance that is also dangerous, but may be only slightly more dangerous. Also, it is important to note that these studies were conducted over 8 years ago and it is possible their information is outdated. In general, it is important when learning whether or not something may be harmful, to ensure that your source is credible and addressing all of the important topics. These articles in particular should not be trusted as the total truth.

Overall, the truth behind alcohol and marijuana use is that they are harmful, and the vast majority of legitimate evidence is that they are most harmful when a person’s brain is still developing. From my research I understand that a wide range of areas can be negatively impacted by alcohol and marijuana use as a teenager: memory, learning, planning, judgement, decision making, impulse control, language, emotions, emotional behavior, and motivation. All of these abilities are crucial in allowing a person to function normally. In addition, all of these things are vastly important when it come to education and work, more so than any other situations. School tests ability to memorize, learn, plan accordingly, and requires a lot of motivation. Thus, not being able to do these things well would make being successful in school much more of a struggle. In addition, struggling to control impulses and emotion, and make adequate decisions could cost one their job. Also, a minor in possession is a serious legal situation that could put education at risk and pose a challenge when finding a future job. In conclusion, I understand the dangers of alcohol and marijuana use from short term physical danger to long term mental health and career consequences. For those reasons, I will say, “I’ll pass,” to alcohol and marijuana until I’m 21. #PassOnIt

South Bay Teen

Works Cited

Again, Alcohol Think. Impact of Alcohol on the Developing Brain,

“The Effects of Drugs and Alcohol on the Adolescent Brain.” Science and Management of Addictions,

“Fact Sheets - Underage Drinking.” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, 20 Oct. 2016,

Heid, Markham. “Here's What We Know About What Weed Does to Teens.” Tonic, 18 Apr. 2017,

“How Drugs Affect Teenage Brains: A Parent's Guide.” The Recovery Village,

Medscape Log In,

Monitor on Psychology, American Psychological Association,

Staff, Written by Casa Palmera. “The Effects of Drug Abuse on Teens.” Alcohol Treatment & Drug Rehab Center San Diego, CA, 23 July 2015,

“Teen Brain Structure Changed With Occasional Marijuana Use, Says Study.” Muir Wood Teen, 20 July 2017,