There is no scientific evidence that medicinal cannabis is effective in treating people with mental illness, research shows.
Australian scientists have reviewed 83 studies with 3,000 people to reach their conclusion.
They found no evidence that cannabinoids relieved the symptoms of six conditions – depression, anxiety, ADHD, Tourette syndrome, PTSD or psychosis.
Therefore, the use of medicinal cannabis for psychological problems cannot be justified on the basis of current data, they concluded.
This is due to a lack of evidence for their effectiveness and due to the known risks.
Cannabis use, especially those with a high THC content, increases the risk of developing a psychotic illness such as schizophrenia.
And for an estimated one in 10 cannabis users who become addicted, this can cause withdrawal symptoms such as anxiety and insomnia.
There is no scientific evidence that medicinal cannabis is effective in treating people with mental illness, research shows
THC is the most important psychoactive substance in marijuana that gives users a high and can also cause anxiety in some smokers.
CBD, on the other hand, is believed to be responsible for some therapeutic effects of cannabis, such as pain relief and relaxation.
Medical cannabis has been shown to treat a wide range of conditions, including arthritis and MS, as well as in patients with chronic attacks.
But the new findings, published in The Lancet Psychiatry magazine, found insufficient evidence that medicinal cannabinoids improve general health problems or their symptoms.
However, they saw a slight improvement in anxiety in people with other medical problems, such as chronic pain or multiple sclerosis.
Cannabis is increasingly being made available throughout the world for medicinal purposes, including for the treatment of mental disorders.
Medical cannabinoids include medicinal cannabis, pharmaceutical cannabinoids and their synthetic derivatives, THC and CBD.
HOW WILL MEDICAL CANNABIS WORK?
A broad term for any type of cannabis-based drug used to relieve symptoms.
Some products that are claimed to be medicinal cannabis, such as CBD oil or hemp oil, are legally for sale as food supplements at health stores.
But there is no guarantee that these are of good quality or offer health benefits.
And some cannabis-based products are available by prescription as medicinal cannabis. These will probably only benefit a very small number of patients.
Epidiolex for children and adults with epilepsy
Epidiolex is a highly purified liquid that contains CBD (cannabidiol).
CBD is a chemical in cannabis that has medical benefits.
You don't get high because it contains no THC, the psychoactive chemical in cannabis.
Epidiolex does not yet have a license in the UK, but is currently running through the licensing system.
In the meantime, the drug can be prescribed without a license for patients with Lennox-Gastaut syndrome and Dravet syndrome (both rare forms of epilepsy).
Nabilone for chemotherapy patients
Many people who receive chemotherapy will have periods in which they feel sick or vomit.
Nabilone can be prescribed by a specialist to relieve these symptoms, but only when other treatments have not helped or are unsuitable.
Nabilone is a medicine, taken as a capsule, that has been developed to work in the same way as THC.
The drug is registered in the UK.
This means that it has passed rigorous quality and safety tests and proven to have a medical benefit.
Nabiximols (Sativex) for MS
Nabiximols (Sativex) is a cannabis-based medicine that is injected into the mouth
It is licensed in the UK for people with MS-related spastasticity that has not improved with other treatments.
But its availability on the NHS is limited. The National Institute for Health and Care Excellence (NICE) does not recommend NHS doctors to prescribe Sativex because it is not cost effective.
There is some evidence that medicinal cannabis can help certain types of pain, although this evidence is not yet strong enough to recommend it for pain relief.
Lead author Louisa Degenhardt, professor of addictions at the University of New South Wales in Sydney, Australia, said: & # 39; Our findings have important implications in countries where cannabis and cannabinoids are made available for medical use.
& # 39; There is a remarkable absence of high-quality evidence to properly assess the effectiveness and safety of medicinal cannabinoids compared to placebo.
& # 39; As long as there is no evidence of randomized controlled trials, no clinical guidelines can be drawn up about their use in mental disorders. & # 39;
She continued: In countries where medicinal cannabinoids are already legal, doctors and patients need to be aware of the limitations of existing evidence and the risks of cannabinoids.
& # 39; These should be considered when considering to treat symptoms of common mental illness.
& # 39; Those who decide to continue should be carefully monitored for positive and negative mental health effects from the use of medicinal cannabinoids. & # 39;
As part of their analysis, the researchers looked at 83 published studies.
Forty of these were randomized controlled trials and the remaining 43 were open-label studies, in which participants knew what treatment they were taking.
Of the 83 studies, 42 looked at depression, 31 at anxiety, eight at tourette syndrome, three at ADHD, 12 at PTSD and 11 at psychosis.
A few randomized controlled trials investigated the role of CBD or medicinal cannabis – most looked at THC, with or without CBD.
The authors discovered that pharmaceutical THC improved anxiety symptoms in individuals with other medical conditions – in seven studies involving 252 people.
However, this may be due to improvements in the primary medical condition, the researchers say.
They suggest that further studies should explicitly study the effects of cannabinoids on anxiety and depression.
Pharmaceutical THC, with or without CBD, worsened negative symptoms of psychosis in one study in 24 people.
It had no significant impact on other primary outcomes for the psychiatric disorders investigated, they found.
THC also increased the number of people who had side effects in ten studies by 1,495 people compared to placebo in all six psychiatric disorders studied.
The researchers say the review points to the limited evidence and the low quality of evidence that exists around the use of cannabinoids for the treatment of mental illness.
Professor Degenhardt added: & # 39; Cannabinoids are often advocated as a treatment for various mental illnesses.
& # 39; Countries that allow medicinal cannabinoid use are likely to see a higher demand for such use.
Art Doctors and consumers should be aware of the low quality and quantity of evidence for the effectiveness of medicinal cannabinoids in the treatment of mental disorders and the potential risk of side effects.
Australian scientists have reviewed 83 studies with 3,000 people to reach their conclusion. They found no evidence that cannabinoids relieved the symptoms of six conditions – depression, anxiety, ADHD, Tourette syndrome, PTSD or psychosis
& # 39; Given the likely importance but little evidence to guide patients 'and clinicians' decisions about cannabinoids for mental health, there is an urgent need for randomized controlled trials to inquire whether there are benefits of cannabinoids for these indications. & # 39 ;
The authors emphasize that their analysis and conclusions are limited by the small amount of data available.
They also note that most studies are based on pharmaceutical cannabinoids rather than medicinal cannabis.
Ian Hamilton, a lecturer in addiction and mental health at the University of York, said: At first glance, this research appears to be pouring cold water on the claims of patients and those who sell cannabis products for mental health.
THE DIFFERENCES BETWEEN THC AND CBD
Tetrahydrocannabinol (THC) and cannabidiol (CBD) are both derived from the cannabis plant.
Together they are part of the cannabinoid group of compounds found in hashish, hash oil and most types of marijuana.
THC is the psychoactive substance responsible for the euphoric, & # 39; high & # 39; feeling that is often associated with marijuana.
THC works together with CB1 receptors in the central nervous system and the brain and creates the feeling of euphoria and anxiety.
CBD does not fit well in these receptors and actually reduces the effects of THC and is not psychoactive.
CBD is thought to help reduce anxiety and inflammation.
& # 39; The researchers searched more thoroughly for evidence than anyone so far, they couldn't find anything that supports the use of these products for common mental problems.
& # 39; This will undoubtedly frustrate people who think their mental health has improved after trying cannabis products, they may feel that their experiences are not appreciated or listened to.
& # 39; Although this review could not find evidence for the use of cannabis, it is not the same as saying that they are not effective.
Professor Hamilton said there were two important factors to consider.
He added: & # 39; First, the researchers point to a lack of studies that examine these products for psychological problems.
Ten Second, no one is average, so it may be that these products do not improve the mental health of many people, but that they help some people, although the only way to find out who these people are is by let them try the products.
& # 39; Unfortunately, traditional drugs used to treat mental health issues can cause people to have unwanted side effects and require patients to continue for a while.
& # 39; It is clearly important to find alternatives that have fewer side effects. It is also possible that some patients consider cannabis as a more natural compound compared to synthetic traditional medicines. & # 39;
Dr. Tom Freeman, CEO of the Addiction and Mental Health Group at the University of Bath, said the analysis reinforced the view that there is insufficient evidence to prescribe medicinal cannabis to people with mental illness.
He added: & # 39; The quality of the evidence is also low for the use of cannabinoids in the treatment of other medical indications, as set out in draft recommendations of the National Institute of Health and Care Excellence (NICE).
& # 39; Given the high demand from patients for access to these drugs, further research is urgently needed to strengthen the evidence.
& # 39; The only way for patients to access these drugs at this time is through a private prescription that requires huge costs, or through the illegal market that carries the risk of prosecution, as well as unknown product content, quality and safety. & # 39;
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