A Huge Study Finds a Link Between Cannabis Use in Teens and Psychosis Later

Over the past decade, marijuana use among teens has steadily increased — alongside a growing perception that cannabis is “natural,” “safe,” or even therapeutic. But a new large-scale longitudinal study is raising serious concerns about the long-term mental health impact of adolescent cannabis use.

The findings are sobering: teens who use cannabis are at significantly higher risk of being diagnosed years later with bipolar disorder, psychotic disorders, depression, and anxiety.

For parents, educators, and clinicians, this information cannot be ignored.

A Landmark Study with Strong Design

The study, published in JAMA Health Forum, analyzed health data from approximately 460,000 adolescents in the Kaiser Permanente system in Northern California. Participants were followed until age 25.

What makes this study particularly important is its design:

• Annual substance-use screenings were included.
• Mental health diagnoses were tracked through medical records.
• Researchers excluded teens who already showed psychiatric symptoms before cannabis use.

Dr. Lynn Silver, a pediatrician and researcher at the Public Health Institute and one of the study’s authors, explained that researchers specifically examined cannabis use before any evidence of psychiatric conditions — helping answer the long-standing “chicken or egg” question:  Does cannabis contribute to mental illness, or do teens with emerging symptoms use cannabis to self-medicate?

This study suggests cannabis use may come first.

The Most Concerning Findings: Bipolar and Psychosis

Teens who reported cannabis use had twice the risk of developing:

• Bipolar disorder (alternating episodes of depression and mania)
• Psychotic disorders, including Schizophrenia

Although only about 4,000 teens in the total sample developed each of these conditions, they are among the most serious and disabling mental illnesses.

Psychiatrist Dr. Ryan Sultan of Columbia University, who was not involved in the study, described the findings as “very, very, very worrying.”

Why?

Because bipolar disorder and psychosis are not mild or transient conditions. They often require lifelong treatment, can severely impair functioning, and carry enormous societal costs. Schizophrenia alone has been estimated to cost the U.S. roughly $350 billion per year in healthcare expenses, lost productivity, and disability.

Increased Risk for Depression and Anxiety

The study also found elevated risk for more common mental health conditions:

• Depression increased by about one-third
• Anxiety increased by about one-quarter

Notably, the link between cannabis use and depression/anxiety was stronger in younger teens. The younger the adolescent’s brain at first use, the greater the risk.

This reinforces a critical biological reality:

The adolescent brain is still developing.

Cannabis interacts with the brain’s endocannabinoid system — a system involved in mood regulation, reward processing, and neural development. Interfering with this system during critical developmental windows may disrupt normal neural wiring.

The Developing Brain: Why Age Matters

Adolescence is a period of:

• Synaptic pruning
• Rapid frontal lobe development
• Emotional regulation maturation
• Risk/reward system calibration

Introducing psychoactive substances during this time may alter neural pathways in ways that increase vulnerability to psychiatric disorders.

Silver noted that younger brains appear especially sensitive to cannabis exposure. The data suggest earlier use may carry a greater long-term risk.

“Playing with Fire”

Clinicians are increasingly observing what the data now support.

Dr. Sultan reports seeing more teens in his practice who use cannabis and subsequently develop worsening anxiety, depression, bipolar symptoms, or psychosis.

Mental health disorders are complex. Genetics, trauma, stress, and environmental factors all contribute. Cannabis is not the sole cause of these conditions.

But for some vulnerable teens, it may act as a trigger.

When someone experiences a psychotic or manic episode in the context of cannabis use, clinicians often warn them not to use again.

Why?

Because repeated episodes can become harder to reverse. Severe mood and psychotic episodes may have neurotoxic effects, contributing to more rapid cognitive decline over time.

In Sultan’s words, using cannabis in these situations is “playing with fire.”

Legalization and the Perception of Safety

As cannabis legalization expands across the United States, public perception has shifted dramatically. Many teens now see marijuana as:

• Natural
• Stress-relieving
• Safer than alcohol
• Non-addictive

However, “natural” does not mean neurologically harmless — especially for developing brains.

The U.S. cannabis market is worth tens of billions of dollars annually. Yet if even a small increase in severe psychiatric illness results from adolescent exposure, the societal cost could rival or exceed industry revenue.

What This Means for Parents and Professionals

For those of us working with adolescents and families, this research highlights several important action steps:

1. Prevention Still Matters

Delaying first use appears critical. The younger the brain, the higher the risk.

2. Screening Is Essential

Routine screening for substance use in pediatric and mental health settings can identify early use patterns.

3. Education Must Be Balanced and Evidence-Based

Fear-based messaging often backfires. But minimizing risks is equally harmful. Teens deserve honest conversations about real neurological vulnerability.

4. Watch for Early Warning Signs

If a teen using cannabis begins showing:

• Paranoia
• Hallucinations
• Extreme mood swings
• Sudden behavioral changes
• Severe anxiety or depression

Immediate evaluation is warranted.

A Nuanced but Urgent Message

This study does not claim cannabis causes mental illness in every teen who uses it.

It does, however, suggest a significantly increased risk, particularly for severe and life-altering disorders.

For families navigating today’s cultural normalization of cannabis, the takeaway is clear:

Adolescent brains are still under construction. Introducing powerful psychoactive substances during this phase may carry consequences that unfold years later.

The conversation around teen marijuana use needs to evolve from “Is it legal?” to “Is it safe for a developing brain?”

The evidence increasingly suggests it is not nearly as safe as many believe.

Expert Recovery Coaching for Marijuana Addiction

Addiction is another significant danger of frequent marijuana use. Overcoming a cannabis use disorder requires compassionate, professional guidance. At R&A Therapeutic Partners, Ray Estefania and Ana Moreno bring over 40 years of combined experience in mental health and addiction counseling, supporting you in your goals of achieving long-term sobriety.

Our approach includes:

• Ongoing coaching to manage life’s challenges and prevent a relapse.
• Tailored strategies for reinforcing healthy habits and maintaining your sobriety in everyday life.
• Dedicated assistance to help you stay on track as you rebuild your confidence.

Reach out today to learn more about our suite of specialized services.

At R&A Therapeutic Partners, Raymond Estefania and Ana Moreno specialize in substance use and mental health disorder evaluations, treatment, intervention, and therapeutic/educational consulting for clients throughout the greater South Florida area, as well as nationally and internationally. For more resources and information, please visit Therapeutic-Partners.com or on Facebook.

At R&A Therapeutic Partners Raymond Estefania and Ana Moreno specialize in substance use and mental health disorder evaluations, treatment, intervention and therapeutic/educational consulting for clients throughout the greater South Florida area, as well as nationally and internationally. For more resources and information please visit Therapeutic-Partners.com or on Facebook.