Cannabis use and its effects on mental health have become a growing area of concern, especially when it comes to psychosis. Research suggests there is a strong link between cannabis use, psychosis symptoms, and the dopamine system in the brain. This article will explain how cannabis may affect the risk of psychosis by changing dopamine activity, focusing on cannabis and psychosis on the dopamine system and related mechanisms. If you’re worried about cannabis use or want to understand the science behind it, this guide will provide clear and useful information for you.

Understanding Cannabis Use and Psychosis

What Is Cannabis Use Disorder (CUD)?

Cannabis Use Disorder (CUD) is a term used when someone finds it hard to control their cannabis use, even when it causes them problems. This might mean cravings, withdrawal symptoms, or using more than intended.

Why does this matter? Because CUD is not just about habit. It’s strongly linked to serious mental health concerns, especially psychosis. Psychosis isn’t just stress or anxiety. It’s a condition where a person loses contact with reality, often experiencing hallucinations, false beliefs, confusion, or paranoia.

The Link between Cannabis and Psychosis

The connection between cannabis and psychosis is supported by many scientific studies. People who use cannabis regularly, or in high doses, have a higher risk of psychosis. This includes experiencing symptoms like hallucinations and paranoia, and even developing full psychotic disorders like schizophrenia.

But it’s important to note that not every cannabis user will develop psychosis, and not everyone with psychosis has used cannabis. What is clear, though, is that the more you use, and the younger you start, the greater the risk. Vulnerable individuals (including those with a family history of psychosis) are especially at risk.

Learn more about the link between Cannabis and Psychosis as below.

Cannabis & Psychosis – The Not-So-Silent Epidemic (Part One)

Cannabis & Psychosis – The Not-So-Silent Epidemic (Part Two)

Cannabis and Psychosis on the Dopamine System

To really grasp why cannabis increases the risk of psychosis, we have to look at what’s happening inside the brain, focusing on dopamine.

What Is Dopamine?

Dopamine is a chemical messenger that plays a big role in mood, reward, and how we interpret the world around us. Think of it as the brain’s “feel good” signal, but also key for attention and perception. The “dopamine hypothesis” of schizophrenia argues that too much dopamine activity in certain brain regions can trigger psychotic experiences.

How Does Cannabis Affect Dopamine?

Cannabis, especially its main ingredient THC (Δ9-tetrahydrocannabinol), directly influences the dopamine system. When someone uses THC, it sparks a surge in dopamine in important brain regions like the striatum and cortex. These dopamine bursts mirror those observed in people experiencing psychotic episodes, helping to explain why cannabis sparks psychosis in some users.

Key Point: The more THC you use, the stronger and more lasting the effect on dopamine and your overall risk for psychosis.

What Do Brain Scans Tell Us About Cannabis Psychosis Dopamine Changes?

Science has not stood still. Thanks to special types of brain scans, our understanding of cannabis and psychosis on the dopamine system is becoming clearer.

Confusing Research Findings

Older research using PET scans (a kind of imaging test) showed that THC raises dopamine levels temporarily. However, in people who use cannabis heavily, total dopamine production over time might actually go down. This paradox has baffled scientists. Does long-term cannabis use overstimulate then “wear out” the brain’s dopamine machinery?

Neuromelanin-MRI – A Game Changer

Now, scientists have a new tool to study these changes more precisely. A neuromelanin-sensitive MRI measures neuromelanin levels, a pigment that accumulates as the brain uses and breaks down dopamine. The more neuromelanin, the higher the long-term dopamine activity.

Most dopamine-producing brain cells are packed into two regions, the substantia nigra (SN) and ventral tegmental area (VTA). By scanning these regions, researchers can see how dopamine systems are affected over months (not just minutes) of cannabis use.

Groundbreaking Study on Cannabis, Psychosis, and Dopamine

A recent study led by researchers at McGill University and Western University has brought some real answers to light.

Study Design & Key Groups

• Participants: 61 people split into groups:
  • 36 with no cannabis use disorder (non-CUD)
  • 25 with CUD
  • Some also had first-episode schizophrenia (FES)
• The CUD group had more men and smokers and scored lower on memory and attention.
• Researchers scanned this group again after a year.

Main Results

1. Cannabis Use Disorder Raises Dopamine Activity

People with CUD had clearly higher neuromelanin-MRI signals in the ventral SN/VTA areas of the brain. This means more long-term dopamine activity. These areas are heavily linked to how severe a person’s psychosis symptoms are.

2. Cannabis and Schizophrenia Together Don’t Just Add Up

Interestingly, those with both CUD and schizophrenia didn’t show a simple doubling of dopamine. The effect of CUD was still clear, but schizophrenia didn’t seem to add much extra. This suggests a more complicated relationship, possibly even that the brain “plates out” on dopamine activity at a particular point.

3. Long-lasting Brain Changes

Even after one year, people with CUD still had higher dopamine activity in key brain regions. This suggests brain changes from cannabis are not just a one-time spike but may last a long time, especially with ongoing use.

4. Nicotine Was Not to Blame

Though people with CUD were also more likely to smoke tobacco, the researchers checked and confirmed nicotine wasn’t causing the dopamine spike. The effect was clearly linked to cannabis use.

5. Severity Matters

The higher the neuromelanin-MRI signal, the more severe the cannabis use. This supports a “dose-response” effect, showing that heavier or more regular cannabis use has a bigger impact on the brain’s dopamine system and, in turn, the risk of psychosis.

Why Does This Matter? The Fight for Prevention

Lasting Brain Risks

The evidence is clear. Regular cannabis use, especially when use is heavy or begins in the teenage years, can change major brain systems behind mood and perception. These changes are linked to distressing symptoms like hallucinations and paranoia and may raise the risk of psychotic illnesses like schizophrenia.

When nearly one in five young people use cannabis daily or almost daily, these findings are a public health red flag that can’t be ignored.

Why Is Cannabis so Risky for Youth?

The teenage brain is still developing, especially in areas rich in dopamine like the SN and VTA. Regular exposure to high doses of THC during these critical years may “program” the brain for problems down the road, causing changes that might not be obvious until much later.

The Power of Early Education

The latest studies provide something prevention experts have needed for years: clear biological evidence that cannabis disrupts the very brain systems tied to psychosis. This knowledge equips parents, educators, and health advocates to talk honestly with teens about what’s at stake.

If you’re a parent, teacher, or community leader, here’s how you can help:

• Share the science. Young people respect facts, not fear campaigns.
• Spot the warning signs. Watch for changes in thinking, suspiciousness, or withdrawal in known cannabis users.
• Support those struggling. Encourage anyone finding it hard to quit cannabis to seek support from professionals.
• Counter the “natural = safe” myth. Just because cannabis is a plant doesn’t mean it’s risk free.

Where Should the Science Go Next?

While the current findings are sobering, we must remember that the study was fairly small and had more males than females. Larger, long-term studies, especially with more female participants, are vital. It’s also important to explore questions like:

• Can dopamine system changes be reversed if a person quits cannabis for good?
• Are some people genetically more at risk?
• What amount of use is “too much” for the brain?

Protecting Your Brain Health Starts Now

The message from the latest research is strong. Avoiding cannabis use, especially frequent or heavy use, helps guard your dopamine system and lowers your risk of psychosis. If you or someone you know is struggling, reaching out for help is the best step you can take for long-term brain health.

What to Remember & Next Steps

• Cannabis and psychosis on the dopamine system is a real, proven link.
• Regular cannabis use changes dopamine regulation – and these changes may last.
• Early prevention and real science-based education save futures.
• If you have concerns about your cannabis use, talk to a health professional today.

Source: Jama Network , News-Medical.Net