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Can Cannabis Help With Schizophrenia?


The use of cannabis as a part of treatment for schizophrenia is a topic of much debate. On one hand, research indicates that cannabis use, particularly during adolescence, is associated with an increased risk of schizophrenia. On the other hand, there is research showing that the cannabinoid CBD may have antipsychotic effects.

These findings point to the involvement of the body’s endocannabinoid system in schizophrenia and the potential of CBD-rich strains or CBD-only cannabis preparations to improve the condition.

Here’s what the research says about the link between the endocannabinoid system and schizophrenia, and the ways in which CBD-rich cannabis may be able to help.

How Cannabis Works on Schizophrenia 

The endocannabinoid system (ECS) exists in all vertebrates and helps regulate crucial functions such as sleep, pain, and appetite. The human body produces its own cannabinoids, which modulate and activate its various functions, but as its name suggests, the endocannabinoid system can also be modulated and activated by cannabinoids found in the cannabis plant. Because the entire system was only discovered in the past 30 years, scientists still have much to learn about the myriad ways cannabis affects the human body.

The cannabis plant contains active compounds called cannabinoids. THC and CBD are the best known as well as the most abundant.

The key difference between the two is that THC is psychotropic, which means it causes the mind-altering high attributed to cannabis, whereas CBD is non intoxicating. THC, CBD, and other cannabinoids can influence our health by interacting with the ECS. 

Recent research points to the involvement of the ECS in psychosis and schizophrenia. In particular, early human studies suggest that the levels and function of endocannabinoids and cannabinoid receptors are altered in schizophrenia.

For example, a 2003 study found that people with schizophrenia had less CB2 receptors and higher levels of the endocannabinoid anandamide. Remission resulted in a decrease of anandamide. 

Similarly, a 2013 study reported reduced levels of CB2 receptors and the two main enzymes (NAPE and DAGL) that build endocannabinoids in people who experienced their first episode of psychosis.

Meanwhile, several studies have highlighted that certain variations of cannabinoid receptor genes are associated with an increased risk of schizophrenia, meaning that some people are genetically predisposed to developing the condition.

One 2002 study found that a specific variation of the CB1 gene was associated with an increased risk of schizophrenia. Similar findings were reported by 2006 and 2008 studies of the CB1 gene.

A 2010 study of healthy individuals and those with schizophrenia revealed that people with a genetic variation resulting in reduced CB2 receptor function were more likely to have the condition. 

Finally, numerous postmortem and neuroimaging studies report that people with schizophrenia have increased CB1 receptor levels in certain regions of the brain. This finding is particularly interesting because it may help explain why the use of cannabis with high levels of THC, a cannabinoid that binds to CB1 and the main one responsible for cannabis’s mind-altering effects, also causes susceptible individuals to develop or worsen psychotic symptoms. 

Taken together, these findings suggest that altered ECS function may be involved in schizophrenia and make people susceptible to developing the disorder. However, they also reveal the promise of using cannabinoids — and CBD in particular — to treat schizophrenia.

Medical Studies on Cannabis and Schizophrenia

Research suggests that the effectiveness of cannabis in treating schizophrenia depends largely on the THC and CBD levels of the given preparation.

Some studies show that THC promotes psychotic symptoms. This may explain why many other studies have concluded that there’s a strong link between smoking strains of cannabis with lots of THC (marijuana) and the worsening or development of schizophrenia.

In sum, there is a growing body of evidence that THC-rich cannabis can worsen psychotic symptoms, but that as a 2013 review paper puts it, “there is mounting evidence supporting the therapeutic use of CBD to treat schizophrenic symptoms.”

CBD and Schizophrenia

CBD does not have the psychotropic effects of THC, and is thus often widely-available in jurisdictions where medical marijuana has not been legalized. 

  • One indication of the therapeutic potential of CBD was a 1995 case mentioned in a 2013 review paper, which described a 19-year-old schizophrenic girl whose symptoms improved significantly by taking high daily doses of CBD. The study also asserted that “behavioural and neurochemical models suggest that CBD has a pharmacological profile similar to that of atypical antipsychotic drugs and a clinical trial reported that this cannabinoid is a well-tolerated alternative treatment for schizophrenia.”
  •  A 2012 clinical study reported that CBD improved psychotic symptoms in schizophrenia sufferers as effectively as the antipsychotic medication amisulpride, but with fewer side effects, “potentially representing a completely new mechanism in the treatment of schizophrenia.”
  • Most notably, a 2017 clinical study found that patients treated with CBD saw a reduction of psychotic symptoms, improvement in cognitive function, and increased likelihood of being rated as improved by their doctor. Also, CBD did not cause any significant side effects in the study. 
  • A more recent case report presented a 57-year-old treatment resistant patient with a 21-year history of schizophrenia. The patient suffered from severe hallucinations that were significantly reduced through CBD treatment. Nevertheless, this is anecdotal evidence and further randomized controlled trials should be done.

Lastly, multiple animal studies have demonstrated the antipsychotic benefits of CBD.

Side Effects

THC-heavy cannabis preparations can worsen psychosis and schizophrenia. Other potential side effects include impaired memory and reaction time, increased heart rate, anxiety, paranoia, red eyes, dry mouth, sleepiness, dizziness, and fatigue.

By comparison, CBD is antipsychotic and has even been shown to counteract the psychoactive consequences of THC. However, preparations that contain mainly CBD may  cause minor issues such as diarrhea, low blood pressure (hypotension), dry mouth, lightheadedness, sleepiness, and fatigue.

Cannabis Side Effects


The Cannigma content is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Always consult with an experienced medical professional with a background in cannabis before beginning treatment.

About Schizophrenia


Schizophrenia is a chronic and complicated brain disorder which can have a severe impact on daily life and relationships. Schizophrenia can cause hallucinations, delusions, and a disconnect with reality. With effective treatment, the disease is often controlled, allowing sufferers to lead normal lives. 

Schizophrenia is a relatively common disorder.  It’s estimated that around 1% of the world’s population, or 50-70 million people, suffer from schizophrenia. Schizophrenia is distributed across the world equally; there is no higher incidence in people of a particular gender, living in a specific country, or from a specific ethnic or socio-economic background. This is unlike many other conditions which may be more common among particular groups.

For some reason which is still unknown, schizophrenia appears earlier in men than in women, with an average onset age of 18 in young men and 25 in young women. It is extremely rare for schizophrenia to first develop in children younger than 12 or adults over 40

Schizophrenia is not a fatal condition, but research has found that people with schizophrenia are 2-3 times more likely to die earlier than the general population. This is largely because of poor control of other chronic conditions people develop with such as heart disease, metabolic disease, and serious infections, which can affect people with schizophrenia who aren’t able to care properly for their health. It’s also partly due to a high suicide rate, a result of the individual’s disordered thought processes as well as due to the huge stigma that many people have towards people with schizophrenia. 


The symptoms of schizophrenia can vary drastically between individuals. It often affects people in waves, with periods of more severe symptoms when schizophrenia is active called “relapses,” and periods when there is a relative lack of symptoms called “remission.” 

Some people with schizophrenia only have one psychotic episode, while others might have several but be able to lead normal lives in between them. For other people, their schizophrenia symptoms might be severe most of the time, without improving much between psychotic episodes, and may be hospitalized for months to years.  

Symptoms of schizophrenia are generally divided into positive symptoms and negative symptoms, along with cognitive dysfunction

Positive symptoms include:

  • Hallucinations, like seeing things that don’t exist, hearing voices, and sometimes tasting strange tastes, smelling odd scents, and feeling someone touching you when there is nothing there.
  • Delusions, or beliefs that aren’t grounded in reality. For example, thinking that someone is out to harm you or a disaster is about to happen. Other examples may include believing that you have an amazing ability, thinking that someone else is in love with you, and thinking that particular comments or gestures are aimed at you, when in fact they have nothing to do with you.
  • Catatonia, when someone does not move, speak, or respond for a very long time.

Negative symptoms include:

  • Neglecting personal hygiene
  • Lacking emotion, speaking in a monotone, and refusing to make eye contact
  • Losing interest in or pleasure from activities, foods, and hobbies that they used to enjoy
  • Withdrawing from friends and family
  • Lacking motivation and energy

Cognitive dysfunction may include the following symptoms, among others:

  • A drop in educational performance in school or college
  • Understanding information and using it to make decisions
  • Difficulty focusing or paying attention
  • Confused or nonsense speech
  • Difficulty thinking logically 
  • Conversation that jumps from one topic to the next without an apparent connection
  • Moving very slowly
  • Having trouble making decisions

The period between the appearance of the first symptoms of schizophrenia and someone’s first full psychotic episode is called the prodromal period. It could last for days, weeks, or as long as several years. It’s difficult to spot schizophrenia during the prodromal period, because the symptoms can be very subtle. 

It’s particularly hard to notice the first signs of schizophrenia in teens, since many of the initial symptoms could be attributed to a different cause, like moving house or changing schools, or dismissed as typical teen behavior like withdrawing from friends and family or losing motivation.


People with schizophrenia aren’t likely to notice their own symptoms, so it’s up to those around them like friends and family to identify that something is wrong and facilitate them seeking medical help.

Diagnosing schizophrenia isn’t always straightforward or clear cut. There’s no single test to prove or disprove that someone has schizophrenia, and many of the symptoms overlap with those of other mental health or neurological disorders. 

The doctor will begin by taking a full medical history and carrying out a complete physical examination. They’ll take blood tests and likely order brain imaging tests, to rule out substance abuse and any neurological conditions. If the doctor suspects schizophrenia, they will send the patient to a psychiatrist for further workup and management. 

A schizophrenia diagnosis can be made when an individual has experienced at least 2 of these symptoms over the last 6 months:

  • Delusions
  • Hallucinations
  • Disorganized speech
  • Disorganized or catatonic behavior
  • Negative symptoms

At least one of the symptoms during that period has to be delusions, hallucinations, or disorganized speech. 

Subtypes of Schizophrenia 

There are 5 main types of schizophrenia, and they have different classifications.  

Paranoid type
This is the most common type, and is mainly characterized by delusions and auditory hallucinations that are paranoid in nature, such as thinking that the CIA is after you.  

Disorganized type
Significant problems thinking in general, disorganization, and not much display of emotions 

Catatonic type
This type of schizophrenia is characterized by periods of immobility, almost as if the individual is in a coma. They may not move even if they are exposed to very painful situations, and at first can be misidentified as a coma.  

Undifferentiated type
Where there is a combination of the other subtypes, most often paranoid and disorganized. 

Residual type
Positive symptoms such as hallucinations and delusions are present but to a lower extent than the other types. 

Individuals with symptoms of schizophrenia along with episodes of depression and mania, will be diagnosed with a condition called schizoaffective disorder, which is a combination of schizophrenia and bipolar disorder.  


Scientists are still researching the precise cause of schizophrenia, but it’s generally agreed that it’s caused by a combination of a genetic predisposition and altered brain chemistry, together with environmental factors that trigger schizophrenia. 

People who have damage to specific genes, as well as problems producing key neurotransmitters like dopamine and glutamate, are at more risk of developing schizophrenia. However, even someone with a predisposition to schizophrenia might not develop it unless they are exposed to certain environmental factors. Scientists are still trying to establish exactly what those environmental triggers are, but they can include:

  • Highly stressful or traumatic situations
  • Certain viral infections
  • Toxins and drugs 
  • Hormonal changes, which can explain why schizophrenia so often begins during the teenage and early adult period


There is no cure for schizophrenia and once diagnosed it is a lifelong illness that requires constant management.  Often, the right combination of medication and therapy can enable people with schizophrenia to lead productive and fulfilling lives. Most patients on the right therapy can live independently, or with the support of family and loved ones. However, this is not always the case, and more severe cases may necessitate prolonged hospitalization or living in a long term medical setting for more comprehensive care.  

In general, positive symptoms of schizophrenia are easier to treat than the negative symptoms, which ultimately lead to more disability and inability to function. Effective treatment for negative symptoms of schizophrenia is sorely lacking.  


The most common type of medication for treating schizophrenia is antipsychotic therapy. These drugs can help relieve positive symptoms like delusions and hallucinations. It can take some time to find the right combination for each person. 

First-generation antipsychotics are older drugs that can have more frequent and more severe side effects, but they generally cost less. These include:

  • Chlorpromazine
  • Fluphenazine
  • Haloperidol
  • Perphenazine
  • Oxilapine 

Side effects of these medications may include fatigue, somnolence, stiffness, tremor, restlessness and weight changes. 

Second-generation antipsychotics are newer types of antipsychotics which may be more expensive, and with different side effects.

  • Aripiprazole (Abilify)
  • Asenapine (Saphris)
  • Brexpiprazole (Rexulti)
  • Cariprazine (Vraylar)
  • Clozapine (Clozaril)
  • Iloperidone (Fanapt)
  • Lurasidone (Latuda)
  • Olanzapine (Zyprexa)
  • Paliperidone (Invega)
  • Quetiapine (Seroquel)
  • Risperidone (Risperdal)
  • Ziprasidone (Geodon)

These medications also have significant adverse effects, varying from one to the other, and may include weight gain, somnolence and fatigue, motor symptoms similar to the first generation antipsychotics and poor glucose control. 


Counseling and psychotherapy on an individual and group basis may help people with schizophrenia to readjust their thought patterns. It also provides tools to cope with stress, which could otherwise trigger a relapse, and to recognize and respond quickly to early signs of a relapse.

Social skills and life skills training help people with schizophrenia to interact effectively with the people around them. 

Cognitive remediation teaches people with schizophrenia new learning techniques that help them to compensate for their difficulties in processing and retrieving information. 

Electroconvulsive therapy (ECT) is a procedure that’s carried out under general anesthesia. Electrodes are attached to the scalp, with small electric shocks sent to the brain. This treatment is mainly given to those suffering from severe depression that has been refractory to many therapies. For schizophrenia, it is only used if medication and other therapeutic treatments are not working. 

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