Studies Debunked: Cannabis Does Not Cause Schizophrenia

What is Schizophrenia?

Schizophrenia is a lifelong mental disorder involving a breakdown in the relation between thought, emotion, and behavior. This leads to faulty perception, inappropriate actions and feelings, a withdrawal from reality and personal relationships into fantasy and delusion and a sense of mental fragmentation. While schizophrenia is not curable, it can be treated. The symptoms of schizophrenia fall into three categories: positive, negative, and cognitive.

Positive symptoms: “Positive” symptoms are psychotic behaviors not generally seen in healthy people. People with positive symptoms may “lose touch” with some aspects of reality. Symptoms include:

  • Hallucinations
  • Delusions
  • Thought disorders (unusual or dysfunctional ways of thinking)
  • Movement disorders (agitated body movements)

Negative symptoms: “Negative” symptoms are associated with disruptions to normal emotions and behaviors. Symptoms include:

  • “Flat affect” (reduced expression of emotions via facial expression or voice tone)
  • Reduced feelings of pleasure in everyday life
  • Difficulty beginning and sustaining activities
  • Reduced speaking

Cognitive symptoms: For some patients, the cognitive symptoms of schizophrenia are subtle, but for others, they are more severe and patients may notice changes in their memory or other aspects of thinking. Symptoms include:

  • Poor “executive functioning” (the ability to understand information and use it to make decisions)
  • Trouble focusing or paying attention
  • Problems with “working memory” (the ability to use information immediately after learning it)
Studies debunked: Cannabis does not cause schizophrenia.

Especially among prohibitionists, schizophrenia has long been raised as a potential risk of cannabis use. New research refutes this implied causal relationship and clarifies the relationship between marijuana and mental illness, showing that schizophrenia may lead to cannabis use — not the other way around.

Due to cannabis being a hot topic, those opposed to its use, are looking for reasons to stop the movement to legalizing it in South Africa —And one of those arguments is that it causes schizophrenia. The problem with that, as Matthew Hill from the University of Calgary’s Hotchkiss Brain Institute has published, is that no one has ever proved it to be true. Matthew Hill, writing in the journal, Nature, notes that there is no concrete evidence of a connection between cannabis and schizophrenia. As he points out, the incidence of schizophrenia has not gone up since the 1960s, when marijuana use became popular in the U.S. and Europe. In addition, countries in which a large segment of the population uses cannabis do not have higher schizophrenia rates.

“Cannabis does not cause schizophrenia.” This is the conclusion of Professor David Nutt‚ psychiatrist‚ neurologist and director of the Neuropsychopharmacology Unit at London’s Imperial College. Nutt is testifying in High Court in Pretoria in a civil case brought by Johannesburg residents’ Myrtle Clarke and Jules Stobbs known as “the Dagga Couple”.

Nutt is world-famous for his work comparing the harms of 20 drugs and rating drugs by their level of harm‚ with the findings published in a 2009 article in The Lancet medical journal. Nutt has studied dagga’s links to schizophrenia‚ as this alleged link is often cited by governments as a reason to keep it illegal.

Prof. Nutt told the court that in a thirty-year period from 1970‚ dagga use in the UK increased by 20%. If it caused schizophrenia‚ Nutt said he expected the rise in cannabis use to increase new cases of the disease. The UK did not see an increase in schizophrenia. “This shows cannabis cannot cause schizophrenia. Schizophrenia is a very rare disease. ”

Dr. Suzi Gage, one of the researchers at Bristol’s School of Experimental Psychology told Science Daily that the data seems to suggest that schizophrenia can lead to cannabis use, not vice a versa: “Our results use a novel method to attempt to untangle the association between cannabis and schizophrenia. While we find stronger evidence that schizophrenia risk predicts cannabis use, rather than the other way round, it doesn’t rule out a causal risk of cannabis use on schizophrenia,”

In the issue for NORML 2007, a report on ‘Cannabis, Mental Health, and Context: The Case For Regulation’, the following was noted by Paul Armentano, the Deputy Director of NORML. The literature review hypothesizes that cannabis use does not cause the psychosis, but rather, that subjects susceptible to the disorder are more likely to engage in the early-onset use of the substance,”  “Evidence reviewed here suggests that cannabis does not in itself cause a psychosis disorder, rather, the evidence leads us to conclude that both early use and heavy use of cannabis are more likely in individuals with a vulnerability to psychosis.”

Medical Cannabis and treating psychotic disorders

A non-psychoactive cannabinoid known as CBD may have beneficial effects for psychotic disorders like schizophrenia. Researchers have found in human trials that CBD is an effective antipsychotic. CBD is considered to be a safe and well-tolerated medication that does not pose the same degree of risk as conventional antipsychotic drugs. Larger clinical trials are still required to determine whether CBD should be prescribed by doctors for psychotic disorders.

Unlike CBD, THC may worsen symptoms of psychosis, and is not recommended for patients with psychotic disorders.

Conclusion

MCDSA proposes a need for sane, humane drug policy in South Africa. We argue that health risk concerns, call for regulation, not criminal prohibition. That way, cannabis’ use among more potentially vulnerable populations such as adolescents may be better discouraged through education and reduced access.

Written by Zara Martin, January 2018

Disclaimer: Medicinal Cannabis Dispensary (MCDSA) aims to be a hub of information about medicinal cannabis, healthy living and the latest scientific research. The views expressed in this article do not necessarily reflect those of MCDSA. Always consult your doctor before starting a new treatment

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