Cannabis Has Changed. The Risks Have Too.

Note:

We’re sharing this today, April 16th, four days before April 20th, a date widely associated with cannabis use. If you have a child in 8th grade or older, this is a good opportunity to have a clear, calm conversation about expectations before the weekend.

You don’t need to cover everything. What matters most is that your child hears your perspective, understands your values, and knows they can come to you with questions or concerns.

Even a brief check-in can make a difference.

By Kevin Phair | Prevention Ed 

The cannabis that exists today is not the same as the cannabis people were using a generation ago. Students, parents, and educators are navigating a landscape that is more potent, more accessible, and more aggressively marketed than at any point in history. One of the most common misconceptions is the belief that cannabis is safer because it has been legalized in many places around the world. Ironically, the drug may present more risk to users than ever before.

This is not about fearmongering. It is about understanding how the drug has changed, what the research actually tells us, and making sure students, parents, and educators are part of the conversation.

More Potent Than Ever

THC potency has increased by approximately 650% since the 1990s. In the 1960s and 70s, the average THC content in cannabis flowers was around 1%. By the 1980s and 90s, it had climbed to 3 to 5%. Today, the average sits between 23 and 26%. The highest-potency flower on the market clocks in at 38%, and concentrates, increasingly available in vape cartridges, wax, and edibles, can reach up to 99%.

THC, or tetrahydrocannabinol, is the chemical compound in cannabis responsible for its psychoactive effects. It is what makes a person feel high, and it is what drives the health risks associated with use.

If alcohol had gotten stronger at the same rate cannabis did, 1 shot in the 90s would now hit like 7.5 shots of liquor today. Different decade. Different drug. More potent. More products. More risk.

This matters because the risks we associate with cannabis are directly tied to potency. A 2022 systematic review in The Lancet Psychiatry  found that high-potency cannabis users are significantly more likely to develop addiction and significantly more likely to experience a psychotic disorder, including schizophrenia. The European Monitoring Centre for Drugs and Drug Addiction reported a 76% increase in people entering treatment for cannabis addiction over the past decade. The formula is not complicated: potency goes up, addiction risk goes up, mental health impact goes up.

Still Under Construction. THC Gets in the Way

Brain development is a long, gradual process that continues well into the twenties and beyond (the commonly cited figure is age 25, though more recent studies suggest key development extends into the early 30s). During adolescence, the brain is building connections, pruning unused pathways, and maturing the prefrontal cortex, the region responsible for decision-making, impulse control, emotional regulation, and future planning. The endocannabinoid system plays a direct role in guiding this process. When a young person uses cannabis, THC disrupts that natural guidance system, actively interfering with how the brain develops.

Research consistently links regular adolescent cannabis use to measurable declines in memory, attention, and processing speed. A landmark longitudinal study associated heavy adolescent cannabis use with IQ decline of up to 8 points by the late 30s, though the size of this effect remains debated.

Those numbers reflect something deeper. THC doesn't affect the brain in one general way. Here are five specific areas THC disrupts during critical years of adolescent brain development. 

The 5 M’s of THC and the Adolescent Brain

Motivation

Adolescence is when the brain is learning how to pursue goals, push through effort, and connect work to reward. THC doesn't just create a temporary high. It interrupts that practice. It's like trying to learn a new sport while someone keeps changing the rules mid-game.

THC acts on CB1 receptors in the reward system, influencing dopamine signaling and how the developing brain processes rewards. Instead of strengthening healthy decision-making pathways, the brain reinforces reward-seeking shortcuts. It starts prioritizing quick, artificial rewards over slower, real-life ones like relationships, goals, and achievement.

In real life, parents and teachers sometimes notice this as decreased effort in school, losing interest in activities a teen once loved, or difficulty following through on goals.

Motor Skills

The brain is refining coordination, reaction time, and physical control throughout adolescence.

THC disrupts this process. It affects areas of the brain responsible for movement and balance, and slows communication between regions at a time when those connections are still being refined. Research links adolescent cannabis use to changes in white matter structure in regions involved in coordination and learning.

Because THC is stored in body fat, metabolites can linger for days or weeks. Functional impairment usually resolves within hours, but frequent use means repeated exposure before the brain has fully cleared the last dose.

For a teen learning to drive or competing in sports, this matters. Slower reflexes are a real safety issue behind the wheel, and gaps in coordination during a critical learning window can shape how athletic skills develop long term.

Maturity

Through the mid-twenties, the brain is developing the ability to manage emotions, control impulses, and respond thoughtfully rather than react in the moment. This growth is driven by the prefrontal cortex, which is learning how to pause, regulate emotional responses, and consider consequences before acting.

THC interferes with this process. It acts on the endocannabinoid system, which helps regulate mood, stress, and communication between brain regions, including the connection between the prefrontal cortex and the amygdala, the part of the brain that drives emotional reactions.

THC overstimulates that system. In the moment, this amplifies emotional reactions while weakening the brain's ability to manage them. Adult brains are affected too, but adolescent brains are particularly vulnerable because these circuits are still maturing.

In practical terms, a teen who would normally pause and think through a social conflict may react impulsively instead. They may be more easily triggered by stress and harder to calm down, which parents and teachers often experience as increased anxiety or emotional volatility.

Memory

Adolescence and early adulthood are a critical time for learning and memory, and it's when the brain is put to the test by academics. The brain is actively building the ability to take in new information, store it, and use it over time. This process is centered in the hippocampus and supported by strong communication between brain regions.

As these systems develop, the brain is also strengthening its "highways." Connections between brain cells are insulated with myelin, which helps information move quickly and efficiently. This is what allows students to keep up with reading, follow complex ideas, and connect new learning to what they already know.

THC interferes with this process. Research shows it affects how the hippocampus captures and stores new information, along with communication between brain regions. In the moment, this looks like difficulty focusing, losing track of what was just said, or forgetting why you walked into a room.

Research consistently shows that adolescent cannabis use is associated with impacts on memory, learning, and reading comprehension. For teens still building foundational knowledge, that can translate into falling behind academically during a window they can't get back.

Mental Health 

Many young people who use cannabis say it helps with anxiety, stress, or sleep. The problem is that it doesn't actually resolve those issues. Research consistently shows that regular adolescent use worsens anxiety and depression over time and reduces sleep quality. The short-term relief is real. The long-term cost is too.

The link to psychosis is becoming clearer as more research comes in on today's higher-potency products. A 2022 systematic review in The Lancet Psychiatryfound that daily users of high-potency cannabis have roughly five times the odds of developing a psychotic disorder compared with non-users. For students with a family history or genetic risk of schizophrenia, using cannabis in adolescence appears tobring on symptoms earlier than they would otherwise appear.A 2019 meta-analysis in JAMA Psychiatry covering more than 23,000 young people found that adolescent cannabis use was associated with higher rates of depression, suicidal ideation, and suicide attempts in young adulthood, even after accounting for pre-existing mental health conditions.

The Takeaway, and Where to Go From Here

Not every teen who uses cannabis will be affected the same way, but the risks during adolescence are real because these systems are still developing. The good news is that the adolescent brain is also remarkably adaptable. When use stops, many of these systems can recover, especially with support.

What helps most is open conversation without judgment, strong relationships with trusted adults, and honest, non-moralizing prevention education. Meaningful activities outside of substance use and early intervention when use becomes a pattern also make a real difference.

What Educators Can Do

Talk about cannabis accurately and often. The potency data alone changes conversations. When students understand that THC levels have increased 650% since the 1990s, the discussion shifts from judgment to facts, which is where prevention actually works.

Use data from your own community or from trusted sources like Monitoring the Future (U.S.) or ESPAD(Europe). Prevention Ed’s survey data reflects international school populations across regions. When students see numbers that reflect their world, conversations become more relevant and more honest.

Recognize the mental health overlap. Many students using cannabis are self-medicating. Approaching those conversations with curiosity rather than judgment, asking why and what it does for them can help identify where they need support most and is how trust gets built and real support becomes possible.

What Parents Can Do

Know what is actually available right now. The cannabis your teenager might encounter includes concentrates, edibles, and high-potency vape cartridges, products many young people do not recognize as meaningfully different from lower-risk forms.

Start the conversation before you think you need to. Young people who have honest conversations about substances with trusted adults are less likely to use and more likely to seek help when they need it. You do not need all the answers. You just need to be willing to talk and follow up with the information from a credible source to get your kids the facts they need. 

If your teenager is using cannabis, focus on understanding the context, not just the behavior. The more useful question is not how much, but what is driving it. Stress, sleep, social pressure, or something else. Those answers point to the kind of support that actually helps.

What Matters Most

Prevention is not about scaring people. It is about giving students, parents, and educators the accurate information they need to make real decisions. The adolescent brain is not finished growing. What goes into it, and what stays out of it, matters more than most people realize.

The research is clear. The data is real and the students in our schools deserve adults who are informed, honest, and willing to have the sometimes uncomfortable, accurate conversation about the risks and benefits instead of the easy one.

To learn more about Prevention Ed services and resources, or to schedule professional development for your counseling team, please contact schools@preventioned.org

Sources:

Broyd, S. J., van Hell, H. H., Beale, C., Yücel, M., & Solowij, N. (2016). Acute and chronic effects of cannabinoids on human cognition: A systematic review. Biological Psychiatry, 79(7), 557–567.https://doi.org/10.1016/j.biopsych.2015.12.002

European Monitoring Centre for Drugs and Drug Addiction. (2023). European Drug Report 2023: Trends and developments. Publications Office of the European Union.

Godin, S. L., & Shehata, S. (2022). Adolescent cannabis use and later development of schizophrenia: An updated systematic review of longitudinal studies. Journal of Clinical Psychology, 78(7), 1331–1340.https://doi.org/10.1002/jclp.23312

Gobbi, G., Atkin, T., Zytynski, T., Wang, S., Askari, S., Boruff, J., Ware, M., Marmorstein, N., Cipriani, A., Dendukuri, N., & Mayo, N. (2019). Association of cannabis use in adolescence and risk of depression, anxiety, and suicidality in young adulthood: A systematic review and meta-analysis. JAMA Psychiatry, 76(4), 426–434.https://doi.org/10.1001/jamapsychiatry.2018.4500

Meier, M. H., Caspi, A., Ambler, A., Harrington, H., Houts, R., Keefe, R. S. E., McDonald, K., Ward, A., Poulton, R., & Moffitt, T. E. (2012). Persistent cannabis users show neuropsychological decline from childhood to midlife. Proceedings of the National Academy of Sciences, 109(40), E2657–E2664.https://doi.org/10.1073/pnas.1206820109

Monitoring the Future. (2024). National survey results on drug use, 1975–2024. Institute for Social Research, University of Michigan.

National Institute on Drug Abuse. (2024). Cannabis (marijuana) research report. National Institutes of Health.https://nida.nih.gov/publications/research-reports/marijuana

Petrilli, K., Ofori, S., Hines, L., Taylor, G., Adams, S., & Freeman, T. P. (2022). Association of cannabis potency with mental ill health and addiction: A systematic review. The Lancet Psychiatry, 9(9), 736–750.https://doi.org/10.1016/S2215-0366(22)00161-4

Prevention Ed. (2025). Student substance use and peer perception survey, 2023–2025.