In recent years, marijuana has become more accessible than ever.
With growing legalization and normalization, many teens view it as harmless, “just a natural plant.” But research tells a different story, especially when it comes to the developing adolescent brain.
The Hidden Costs: Marijuana Use and the Adolescent Brain
In recent years, marijuana has become more accessible than ever. With growing legalization and normalization, many teens view it as harmless, “just a natural plant.” But research tells a different story, especially when it comes to the developing adolescent brain.
Adolescence is a critical window of brain development, lasting into the mid-20s. During this time, neural connections are being refined, the prefrontal cortex (responsible for decision-making, impulse control, and judgment) is still maturing, and the brain is more sensitive to outside influences, including substances like marijuana.
How Marijuana Affects the Adolescent Brain
- Memory and Learning Impairment
THC, the psychoactive compound in marijuana, directly affects the hippocampus, the brain’s center for learning and memory. Adolescents who use marijuana regularly may experience difficulties with concentration, short-term memory, and academic performance. - Impact on Motivation and Mood
Teens who use marijuana frequently often report lower motivation, decreased engagement in school, and reduced interest in hobbies. While some use marijuana to manage stress or anxiety, evidence suggests it can actually worsen symptoms of depression and anxiety over time. - Increased Risk of Psychosis
One of the most concerning risks is the association between marijuana use and psychotic disorders. Research shows that early and heavy marijuana use significantly increases the risk of developing schizophrenia or other forms of psychosis, particularly in adolescents with a family history of these conditions.
The Link to Bipolar Disorder and Schizophrenia
Studies indicate that adolescents who use marijuana are at higher risk for mental health disorders, including:
- Bipolar disorder: Marijuana use may exacerbate manic and depressive episodes, complicating treatment and stability.
- Schizophrenia: Heavy, early use (especially before age 16) has been linked to a two- to four-fold increase in risk. The younger the brain is exposed, the higher the vulnerability.
These are not risks most teens, or even many parents—are fully aware of. The perception of marijuana as “safe” can mask its potential for long-term and life-altering consequences.
Why Teens Are More Vulnerable
Unlike adults, adolescents are still developing critical neural pathways for judgment, impulse control, and emotional regulation. Marijuana disrupts these processes, making young people more vulnerable to:
- Risk-taking behaviours
- Poor academic outcomes
- Dependence and addiction (teens are 4–7 times more likely to develop cannabis use disorder than adults)
What Parents and Caregivers Can Do
- Start the conversation early: Talk openly and non-judgmentally about the risks of marijuana.
- Watch for changes: Sudden drops in grades, changes in friends, mood swings, or withdrawal can all be warning signs.
- Offer support, not shame: Adolescents respond best when they feel heard and understood.
- Seek professional help if needed: If marijuana use is already a concern, counselling and family support can make a significant difference.
Final Thoughts
Marijuana may be common and culturally accepted, but for the developing adolescent brain, it can have serious consequences—far beyond the short-term “high.” Understanding the risks, especially the links to bipolar disorder and schizophrenia, empowers families to make informed choices and support their children’s long-term health.
As a counsellor who has worked with youth and families for over 25 years, I believe education and early intervention are key. Together, we can create the awareness and support adolescents need to build healthy futures, free from the hidden costs of marijuana use.
References
- Arseneault, L., Cannon, M., Witton, J., & Murray, R. M. (2004). Causal association between cannabis and psychosis: examination of the evidence. British Journal of Psychiatry, 184(2), 110–117. https://doi.org/10.1192/bjp.184.2.110
- Giedd, J. N. (2015). The teen brain: insights from neuroimaging. Journal of Adolescent Health, 52(2 Suppl), S2–S6. https://doi.org/10.1016/j.jadohealth.2012.05.007
- Lev-Ran, S., Roerecke, M., Le Foll, B., George, T. P., McKenzie, K., & Rehm, J. (2014). The association between cannabis use and depression: a systematic review and meta-analysis of longitudinal studies. Psychological Medicine, 44(4), 797–810. https://doi.org/10.1017/S0033291713001438
- Volkow, N. D., Swanson, J. M., Evins, A. E., DeLisi, L. E., Meier, M. H., Gonzalez, R., ... & Baler, R. (2016). Effects of cannabis use on human behavior, including cognition, motivation, and psychosis: a review. JAMA Psychiatry, 73(3), 292–297. https://doi.org/10.1001/jamapsychiatry.2015.3278