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Can Marijuana Use Cause Schizophrenia?

Isaac Alexis, M.D., AAMA, AMP-BC

Medically reviewed by

Isaac Alexis, M.D., AAMA, AMP-BC

June 18, 2019

As marijuana use becomes more popular – and in some states, even legal – people are taking a closer look at the risks associated with this drug. While more research is needed, there seems to be a direct link between marijuana and schizophrenia. Someone who abuses cannabis and also has schizophrenia will likely need a specialized treatment program to manage these conditions.

While marijuana has been used for centuries, this drug has been in the spotlight in recent years due to its rising popularity and increasing legal status. Previously illegal throughout the nation, marijuana is now legally sold in a number of states, including California and Nevada.

Many people see no harm in marijuana use; in fact, it’s being used more and more often in medical settings as a treatment for various health conditions. And, compared to many other drugs, cannabis does have fewer side effects and risks. However, this doesn’t mean that the substance is completely safe.

One health concern associated with marijuana use is the connection it may have to schizophrenia. Let’s explore the relationship between cannabis and schizophrenia and whether these two are connected.

What Is Schizophrenia?

Schizophrenia is a chronic mental health condition that significantly affects a person’s ability to function in society. The most common symptoms associated with this condition are hallucinations, delusions, and problems with concentration and thinking.

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People with schizophrenia may be unable to determine what is real and not real. They may also have a hard time controlling and expressing their emotions.

Symptoms of schizophrenia fall into four categories: positive, negative, disorganization, and impaired cognition symptoms. The frequency and severity of symptoms will vary from person to person.

Symptoms of schizophrenia include:

  • Positive Psychotic Symptoms — paranoid delusions; hallucinations; distorted beliefs and behaviors
  • Negative Symptoms — an inability or decreased ability to speak, experience pleasure, or make plans
  • Disorganization Symptoms — confusion; disordered thoughts or speaking; abnormal body movements; difficulty thinking logically
  • Impaired Cognition Symptoms — concentration, memory, and attention problems; trouble at work or school

Many people first begin to experience symptoms of schizophrenia in early adulthood. Early signs of this condition may include decreased motivation, relationship problems, and poor school performance.

The severity of symptoms tends to decline as a person ages. However, not taking medication or abusing drugs and alcohol can increase the frequency and severity of symptoms.

Causes Of Schizophrenia

The exact cause of schizophrenia is unknown. Researchers believe that a number of factors may play a role in the development of this condition. It’s also thought that some people are more prone to this condition than others.

Factors that may contribute to schizophrenia include:

  • Genetics — People who have a close relative that has this condition may be more likely to develop schizophrenia themselves.
  • Brain Structure — Individuals with schizophrenia often have differences in the way their brains develop compared to people without this condition.
  • Birth Complications — Complications before and during birth may increase the risk of schizophrenia. These complications may include low birth weight, asphyxia during birth, and early labor.
  • Neurotransmitter Imbalance — Studies have shown that people with schizophrenia often have an imbalance of certain neurotransmitters in the brain. The primary neurotransmitters believed to be affected are serotonin and dopamine.

Additionally, life stressors and drug abuse are believed to act as triggers for this condition. When someone with a predisposition to the condition experiences these triggers, he or she may begin to experience symptoms of schizophrenia.

Does Marijuana Cause Schizophrenia?

Various studies have explored the correlation between using marijuana and the development of schizophrenia. Some research has even shown that people ages 15 and younger who regularly use cannabis are up to four times more likely to develop schizophrenia in young adulthood.

One direct link between marijuana and schizophrenia is the occurrence of psychosis. Psychosis is when a person experiences disrupted thoughts that make it difficult to determine what is real and what’s not. Psychosis is a common symptom of schizophrenia, and marijuana use can trigger this symptom.

Additionally, marijuana may trigger schizophrenic symptoms in people who have a predisposition to the condition. Studies have shown that people who carry certain genes are at a higher risk of developing schizophrenia as a result of marijuana use. These genes, which include COMT and AKT1, affect the chemicals in the brain.

What’s more, using cannabis may cause the symptoms of schizophrenia to begin earlier in life. People often begin to experience symptoms of this condition in early adulthood, but marijuana use can result in symptoms appearing up to three years earlier.

Marijuana may also increase schizophrenic symptoms in someone who already has the condition. Unfortunately, cannabis seems to be a choice drug for individuals with schizophrenia. Research has shown that an estimated half of people with schizophrenia also have a co-occurring marijuana addiction.

Risk Factors Of Marijuana Use And The Development Of Schizophrenia

Marijuana use on its own is not believed to cause schizophrenia when no other risk factors are present. However, when someone has one or more factors related to the development of schizophrenia, cannabis may worsen or trigger the condition.

Risk factors that may influence a person’s chances of developing schizophrenia as a result of marijuana use include:

  • regularly using marijuana at a young age
  • already having symptoms of schizophrenia
  • having a family history of schizophrenia
  • having other underlying mental health conditions

People with any of these risk factors are advised to avoid marijuana use.

Treatment For Co-Occurring Schizophrenia And Marijuana Addiction

When a person has been diagnosed with both schizophrenia and a substance use disorder like marijuana addiction, this is referred to as co-occurring disorders. Co-occurring disorders can make treatment more difficult. However, there are several options that have proven successful in treating these conditions.

Treatment programs that specialize in dual diagnosis are often recommended for people with co-occurring disorders. These programs treat both conditions simultaneously and may include various forms of therapy, medication-assisted treatment, and support groups.

Because both addiction and schizophrenia are chronic diseases, long-term care is often needed. Many people with schizophrenia will need to continue to take medication to manage their symptoms. Support groups like 12-step programs may also be beneficial for people with co-occurring disorders.

To learn more about the link between marijuana use and schizophrenia, contact a treatment specialist today.

WebMD - Schizophrenia and Marijuana: Trigger or Treatment?

NHS - Schizophrenia

The New York Times - Does Marijuana Use Cause Schizophrenia?

American Psychiatric Association - What Is Schizophrenia?

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