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Role of Cannabis

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Role of Cannabis

There are various drugs in the world, and they have a tremendous effect on the brain and body. From cocaine to heroin to nicotine to cannabis, each drug triggers different feelings that can affect your health.

One particular drug that has gained notoriety is cannabis. Cannabis is usually a smoked drug (similar to nicotine in cigarettes), but it can also be eaten. Cannabis has been linked to the development of schizophrenia (due to the harmful effects of cannabis). We will evaluate the research on this topic while acknowledging the effects of cannabis on schizophrenia.

Role of Cannabis Three cannabis leaves StudySmarterCannabis, Flaticon

What is the meaning of cannabis?

Cannabis is a drug derived from a flowering plant. The cannabis plant contains compounds known as cannabinoids. Cannabis can be smoked, eaten and even vaped and has many different names such as marijuana, dope and weed. When smoked, it usually begins to take effect after two minutes; when eaten, after about an hour. How long it lasts varies.

Cannabinoids are drugs/substances that bind to cannabinoid receptors in the brain and body.

The two main active cannabinoids are known as delta-9-tetrahydrocannabinol (d-9-THC, as delta-9-tetrahydrocannabinol is quite a mouthful!) and cannabidiol (CBD).

Brain neurochemistry and the effects of cannabis

Cannabis works by binding d-9-THC to specific sites in the brain and body, acting as a partial agonist (i.e., it has a lesser effect than a full agonist because it has a lesser potency than a full agonist. This can sometimes be advantageous because it can work in tandem with naturally occurring neurotransmitters near your receptors).

Agonist

A chemical that binds to and activates a receptor.

When cannabis is used, d-9-THC binds to receptors in the brain (known as CB1R) that mediate the inhibitory effects of certain excitatory and inhibitory neurotransmitters (e.g., dopaminergic, GABA, and serotoninergic neurotransmitters).

For example, dopamine is strongly involved in the brain's reward system. d-9-THC is thought to inhibit the release of neurotransmitters such as GABA. GABA normally inhibits the release of neurotransmitters such as dopamine and suppresses dopamine neurons. This then consequently leads to an increased release of dopamine and acetylcholine.

d-9-THC binds to the CB1R and less selectively inhibits the release of certain neurotransmitters (you remember, it is a partial agonist).

Cannabis causes the following feelings/effects:

  • Happiness.

  • Giggling.

  • Hallucinations.

  • Psychosis.

  • Drowsiness.

  • Paranoia.

  • A general 'stoned' feeling.

For those who want to know a little more about cannabis and cannabinoids, here is a list of all known major cannabinoids:

  • CBD - Cannabidiol.
  • THC - Tetrahydrocannabinol.
  • CBN - Cannabinol.
  • CBG - Cannabigerol.

There are also other minor cannabinoids:

  • CBC - Cannabichromene.
  • CBF - Cannabifuran.
  • CBR - Cannabiripsol.

Role of Cannabis THC cannabis compound diagram StudySmarterTHC cannabis compound diagram, Flaticon

What is the role of cannabis in schizophrenia?

Considering one of the main effects of cannabis is hallucinations and general psychosis experiences (which can quickly become adverse effects of cannabis, as these experiences can lead to psychotic symptoms in some), we must acknowledge the potential role of cannabis in schizophrenia, as these two effects are positive symptoms in schizophrenia and often one of the first signs of the disorder.

Cannabis doesn't have exclusively harmful effects on a person, but benefits as well. Benefits of cannabis in medical use include helping those suffering from various disorders, such as patients with pain and those with mental disorders such as anxiety and depression (within reason, as excessive use has also been linked to increased anxiety and depression symptoms).

First, we need to determine whether cannabis increases the risk of developing schizophrenia and why this might be the case.Let us first look at genetic predisposition.

Does cannabis increase the risk of developing schizophrenia when genetic risks are involved?

Studies suggest that people who use cannabis have a higher risk of developing schizophrenia if they are genetically predisposed to it than non-cannabis users. Why is this the case?Originally, schizophrenia was thought to be due to a single 'schizogene’ according to the diathesis-stress model (the interactionist approach). Meehl (1962) proposed this thesis, assuming that schizophrenia was due to an internal vulnerability (a diathesis) and an environmental trigger (stressor).Meehl stated that a person who did not have this schizogene would not develop schizophrenia.Today, we know schizophrenia is a polygenetic disorder and consider the environment an important factor.

Gottesman (1991) studied the rate of development of schizophrenia in twins. In the case of monozygotic (MZ; identical) and dizygotic (DZ; not identical) twins, MZ twins had a concordance rate of 48%, whereas DZ had a concordance rate of only 17%. Since identical twins have 100% of their DNA in common, this suggests there is a genetic factor, but the environment also influences (otherwise there would be a 100% concordance rate in MZ twins).

So we know that schizophrenia has genetic factors. How does cannabis affect that?Wainberg et al. (2021), in a cross-sectional study of 109,308 participants, examined how schizophrenic polygenic risk modulates the association between self-reported cannabis use and self-reported psychotic experiences, specifically:

  • Auditory hallucinations.

  • Visual hallucinations.

  • Persecutory hallucinations.

  • Delusions of reference.

They found that the psychotic experiences of cannabis users had an earlier onset and were more distressing for the participants. They found a strong dose-dependent relationship between cannabis use and the above psychotic experiences.A stronger relationship between cannabis use and psychotic experiences was found in individuals with high polygenic risk scores for schizophrenia. This finding suggests cannabis is an overall predictive risk factor for psychotic experiences. Those who are genetically susceptible to schizophrenia are at higher risk for psychotic experiences when using cannabis.

Similarly, Vaissiere et al. (2020) found positive phenotypic correlations in 11 of 12 pairs of cannabis users and schizotypic phenotypes when assessing the genetic overlap between cannabis use and subclinical psychosis (schizotypy).They stated there was a robust association between elevated symptoms of schizotypy and cannabis use.Thus, if an individual has a genetic susceptibility to the development of schizophrenia, it is believed cannabis use contributes to the development of schizophrenia. This is evidenced by the fact that it causes psychosis-like symptoms in those who use cannabis. Genetic susceptibility exacerbates these experiences and can lead to the onset of schizophrenia.

Role of Cannabis StudySmarterCannabis, Flaticon

The AKT1 gene: the role of cannabis in schizophrenia

We mentioned above the d-9-THC compound, which activates the AKT1.The AKT1 gene encodes proteins important for the striatal dopamine receptor signalling cascade (Morgan et al., 2016). This process helps mediate motivational and cognitive control.

  • Studies have found people who carry polymorphisms of the AKT1 gene (particularly those with two copies of the C allele) have a higher risk of developing psychotic disorders when they use cannabis. However, these were retrospective reports - they did not examine the acute effects of current cannabis use and AKT1 associations at the time of cannabis smoking. There was also a family history of psychotic disorders in the patients, so we cannot say conclusively that this is not the determining factor.

  • Morgan et al. (2016) tried to solve these problems. In their study of active cannabis users without a family history of schizophrenia, they found that variations in the AKT1 gene predicted psychotic responses to cannabis (in addition to dependence on the drug). They suggested the AKT1 pathway may be a potential treatment focus area for those who use cannabis and are at risk of developing schizophrenia.

What other roles does cannabis have in schizophrenia?

Cannabis may also impact the development of schizophrenia when we consider other factors such as age.

While the brain is still developing, external factors that affect brain cognition, especially those that trigger psychosis experiences, can irrevocably alter the brain, and studies have noted the impact this has on brain development into adulthood and schizophrenia.

Cannabis can also be used to self-medicate people with schizophrenic symptoms. So when people with schizophrenic symptoms use cannabis to self-medicate, we can not say conclusively whether their symptoms are caused or exacerbated by cannabis.

Cannabis may also be therapeutic, as some studies have shown that people who use CBD have been successful in alleviating their psychosis symptoms. THC can trigger the symptoms, but other substances can help them.

Henquet et al. (2005) studied the effects of cannabis and the development of psychotic symptoms in 2437 adolescents and young adults. They found a dose-response relationship between those who self-reported their cannabis use at baseline and the likelihood of developing psychotic symptoms. Those who reported it were more likely to develop psychotic symptoms at a 4-year follow-up.


Role of Cannabis - Key takeaways

  • Cannabis is a drug derived from a flowering plant that contains various compounds known as cannabinoids. It can be smoked, eaten and even vaped, and has many different names such as marijuana, dope and weed.
  • The main active cannabinoid is known as delta-9-tetrahydrocannabinol (d-9-THC).
  • Cannabis works by binding d-9-THC to specific sites in the brain and body and acting as a partial agonist (i.e., it has a lesser effect than a full agonist). It is said to increase the release of neurotransmitters such as dopamine (involved in the reward pathway).
  • One of the main effects of cannabis is hallucinations and general psychotic experiences. Other effects include drowsiness, giddiness, anxiety, and paranoia.
  • Genetic susceptibility to schizophrenia has been shown to increase by cannabis use, and the AKT1 gene is one example.

Frequently Asked Questions about Role of Cannabis

Cannabinoids drugs are drugs that bind to the cannabinoid receptors within the brain and the body that produce effects similar to that of cannabis.

This depends on what you are smoking. Smoking cannabis, for instance, can affect the development of schizophrenia, but we cannot conclusively say it causes schizophrenia. Many factors influence the chances of developing schizophrenia, some more than others. Genetic vulnerability is a significant factor.

Smoking may help alleviate some of the symptoms of schizophrenia, especially those considered mood disorders (many self-medicate using nicotine and cannabis). Cannabis induces a feeling of euphoria, relaxation, giddiness, and general happiness, so this may help medicate some of the more troubling symptoms of schizophrenia. However, cannabis also causes hallucinations and psychosis experiences, and this may exasperate symptoms of schizophrenia. 

People with schizophrenia may smoke to self-medicate their symptoms. They also might smoke due to an addiction that may have developed before the onset of their symptoms. Smoking is a habit that can be formed outside of schizophrenia, although it has been causally linked to its development. 

Final Role of Cannabis Quiz

Question

What is cannabis?

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Answer

Cannabis is a drug that comes from a flowering plant containing various compounds known as cannabinoids. 

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Question

How long does it take for cannabis to take effect?

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Answer

Two minutes if smoked, up to an hour if eaten.

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Question

How long do the effects of cannabis last?

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Answer

This varies depending on the person.

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Question

What are the two main active compounds in cannabis?

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Answer

The two main active compounds are known as delta-9-tetrahydrocannabinol (d-9-THC) and cannabidiol (CBD).

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Question

What are cannabinoids?

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Answer

Cannabinoids are drugs/substances that bind to cannabinoid receptors in the brain and body. They have similar effects to cannabis.

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Question

How does cannabis work?

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Answer

Cannabis works by binding d-9-THC to specific sites in the brain and body, acting as a partial agonist (i.e., it has a lesser effect than a full agonist because it has a lesser potency than a full agonist. This can sometimes be advantageous because it can work in tandem with naturally occurring neurotransmitters near your receptors).

Show question

Question

How does inhibiting GABA affect dopamine?

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Answer

GABA inhibits the release of dopamine and suppresses dopamine neurons. When you inhibit GABA, more dopamine is released and the neurons are no longer suppressed. Dopamine is no longer inhibited. 

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Question

Is d-9-THC a partial agonist?

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Answer

Yes.

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Question

What are the effects of cannabis?

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Answer

  • Happiness
  • Giggling
  • Hallucinations
  • Psychosis
  • Sleepy
  • Paranoia
  • A general 'stoned' feeling

Show question

Question

How does cannabis increase the risk of developing schizophrenia?

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Answer

It exasperates symptoms in those with genetic vulnerabilities (e.g., AKT1 gene), affecting brain development in young people. It also affects those who use cannabis recreationally and those who self-medicate with cannabis, as it increases symptoms of psychosis. 

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Question

What did Morgan et al. (2016) find in their study?

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Answer

In their study of active cannabis users with no family history of schizophrenia, they found that variations of the AKT1 gene predicted psychotic responses to cannabis (alongside dependence on the drug). 

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Question

What did Vaissiere et al. (2020) find in their study?

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Answer

Vaissiere et al. (2020) found that, when assessing the genetic overlap between cannabis use and subclinical psychosis (schizotypy), positive phenotypic correlations were observed in 11 out of 12 pairs of those using cannabis and schizotypy phenotypes. 

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Question

What are the benefits of smoking cannabis?

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Answer

Relief of pain, self-medicating mood disorders, alleviating anxiety and inducing feelings of happiness, giddiness, and euphoria. 

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Question

What did Meehl (1962) suggest about the genetic components of schizophrenia?

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Answer

He suggested schizophrenia results from the interaction between a schizogene and an environmental stressor.

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Question

What did Wainberg et al. (2021) find in their cross-sectional study?

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Answer

They found that cannabis users psychotic experiences had an earlier onset time, and they caused greater distress for the participant. They found a strong dose-dependent relationship between cannabis use and psychotic experiences.

Those with high polygenic risk scores of schizophrenia showed stronger associations between using cannabis and psychotic experiences. They suggest that cannabis is a predictive risk factor for psychotic experiences, and those genetically vulnerable to schizophrenia may be more at risk to psychotic experiences when using cannabis.  

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