Cannabis – effectless in mental disorders

by Jean-Paul Vuilleumier

An Australian meta-analysis published 28 October (see box) arrives at the conclusion that the use of cannabis and its synthetic derivatives is no help for people with specific mental disorders like depressions or psychosis.
To investigate the use of cannabis and its synthetic derivatives, Australian researchers analysed 83 studies on the consumption of cannabis or its agents tetrahydrocannabinol (THC) and cannabidiol (CBD) in patients with six mental disorders: depression, anxiety, attention-deficit hyperactivity disorder (ADHD), Tourette syndrome, post-traumatic stress disorder or psychosis.
“Actually this is no big surprise”, says Xavier Laqueille, MD, head of the drug addiction department of the hospital Sainte-Anne in Paris. “Cannabis is a well-known risk factor for schizophrenic diseases and aggravates many mental disorders.”

Is cannabis effective against anxiety states?

Some studies show “a small improvement of anxiety symptoms” with THC in patients with other health problems like chronic pain or multiple sclerosis. But according to the article which was published in the British medical journal The Lancet Psychiatry, it was not possible to find out if the effect maybe was due to an improvement of the disease itself.
“Cannabis contains two main active agents, THC and CBD”, Xavier Laqueille explains. “THC is dangerous, even toxic and promotes psychosis. CBD could have positive effects on anxiety states, but very much less than the drugs already available.” The expert on addiction states it more precisely: “Cannabis is not effective against mental disorders, but we find a certain effect against somatic pain. But this has to be confirmed by further studies.”

Use and testing of “therapeutical” cannabis

About 30 countries in the world allow under different conditions the application of “therapeutical” cannabis (about 20 European countries, the USA, Australia, Canada, Israel and some Latin-American countries). According to the study mental disorders are one of the commonest reasons for this use, followed by chronic pain without referring to cancer.
“One of the most striking things about the spread of legislation in multiple countries permitting cannabis/cannabinoids for medicinal purposes is that this is in many instances happening outside of the regulatory frameworks that medicine development typically occurs within,” said Louisa Degenhardt, leading author of the study who was interviewed by AFP.
At the same time the risks related to the use of cannabis are well-proven, she adds and refers to the risk of addiction, the risks of driving under influence of these substances and there is “evidence that people who use cannabis regularly may be at increased risk of developing depression and psychotic symptoms.1
The authors point out the necessity of further high quality studies about this topic – especially with greater numbers of patients, placebo-controls and extended duration. Before this has taken place, “no medical recommendations can be developed for the use of cannabis or its agents for treating mental disorders”, says professor Degenhardt.
In countries where that kind of use has already been legalised, “medical doctors and patients have to be informed about the restricted extent of scientific sound evidence and about the risks of cannabinoids” adds the professor at the National Drug and Alcohol Research Centre of the university of New South Wales, Sydney.
Recently France has green-lighted a two years lasting trial with the prescription of “therapeutical” cannabis. But thereby only the treatment of pain in specific indications is permitted, provided that already existing medicaments are ineffective.    •

Sources:
–    Keystone ATS/Agence Télégraphique Suisse, 29 October 2019
–    Centre national de prévention, d’études et de recherches en toxicomanies (CNPERT), France, drogaddiction.com, 1 November 2019

1    http://www.jamaicaobserver.com/news/poor-evidence-cannabis-improves-mental-health-study_178505?profile=0

Titel and link of the original publication:

“Cannabinoids for the treatment of mental disorders and symptoms of mental disorders: a systematic review and meta-analysis”
www.thelancet.com/journals/lanpsy/article/PIIS2215-0366(19)30401-8/fulltext

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