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The NHS has weighed in on new "valuable research" which suggested that medical cannabis does not improve mental health conditions.

It comes following the new study, conducted by institutions in Australia and the UK, which concluded that there is "scarce evidence" that cannabis-based products are beneficial to those with depression and anxiety, for example.

The research was funded by a variety of sources including the US National Institutes of Health and examined all the evidence available to date on the controversial topic.

Researchers ultimately concluded though that in some cases, taking medicinal cannabis in fact increased the prominence of mental health symptoms such as those experienced by psychosis sufferers.

This analysis attracted media attention and the the NHS has now shared its own thoughts on whether there really is "no evidence" that medical cannabis is beneficial for mental health conditions.

What's considered medical cannabis?

(Image: PA)

Medicinal cannabis is a "broad term," according to the NHS, which refers to a medicine that includes cannabinoid chemicals.

These are natural extracts from the cannabis plant as well as man-made varieties.

Two types of medical cannabis are most prevalent and these are tetrahydrocannabinol (THC) and cannabidiol (CBD).

Products containing these substances are currently available online with some individuals in England and Wales even able to obtain cannabis-based products on prescription.

A "very small number of patients" suffering from epilepsy, nausea and chronic pain due to chemotherapy can be prescribed the drug, though health and government officials previously said they were considering expanding this reach in the future.

What was the latest research?

(Image: Getty Images)

The research was a systematic review, which means that researchers identified previous studies - published between 1980 and 2018 - that had examined the effect of medical cannabis on mental health conditions.

A total of 83 studies were identified as appropriate, involving thousands of participants collectively, and their results were pooled together for a meta-analysis.

The pre-existing studies covered a range of mental health conditions and these included:

depression

anxiety

psychosis

Tourette's syndrome

attention deficit hyperactivity disorder (ADHD)

post-traumatic stress disorder (PTSD)

Of these conditions, depression was the most prominent in the research as it was the subject of 42 studies, with anxiety closely behind in 31 reviews.

PTSD and psychosis were less prevalent in the pre-existing studies and appeared in 12 and 11 studies respectively.

And the remaining two conditions - Tourette's and ADHD - featured in less than 10 studies each and are therefore less researched areas of health.

But despite the fact a large number of trials focused on depression and anxiety, medical cannabis was actually prescribed for these conditions in only a couple of cases - instead often instead provided for chronic pain.

Such studies however explored the effect of such medication on medical health though, hence their inclusion in the new research.

Additionally, nearly all of the evidence looked at medical grade THC and CBD in combination (referred to as THC-CBD) - with only a few looking at CBD alone or other types of medical cannabis.

Participants of the trials primarily took the medical cannabis by mouth, with only a couple of studies looking at vaporised or smoked cannabis.

What were the findings?

(Image: Gareth Fuller/PA Wire)

The pooled results of 7 studies found that THC-CBD led to a small improvement in anxiety symptoms.

There was however no difference to depression symptoms, as reported in 11 trials, with this becoming a trend amongst the other conditions.

None of the studies focused on psychosis, Tourette's syndrome or ADHD found any benefit to symptoms from such medication - though one trial noted an improved quality of life.

The PTSD analysis however suggested that medicinal cannabis made some difference to nightmare frequency and functioning.

Overall, 10 trials (1,495 people) found that THC-CBD in fact doubled the risk of side effects - including the risk of worsening mental health symptoms.

And in 11 trials (1,621 adults), the chance of stopping treatment due to side effects was nearly tripled.

The researchers concluded that there is "scare evidence" to suggest that medicinal cannabis improves any of the previously mentioned conditions.

They however acknowledged "very low-quality evidence" that pharmaceutical THC - with or without CBD - leads to a small improvement in anxiety symptoms for individuals with other medical conditions.

What has the NHS said?

(Image: Dominic Lipinski/PA Wire)

The NHS said it was a "valuable review" that has "gathered all the evidence to date" on the use of medical cannabis in mental health conditions.

It further commented: "What it highlights most of all is the overwhelming poor quality of studies to date, which do not provide good evidence to support the use of medical cannabis for the treatment of mental health conditions."

In the studies, medical cannabis had typically been prescribed to treat other conditions, rather than mental health conditions themselves - which therefore makes such evidence on anxiety, for example, "unreliable and of poor quality."

The NHS even acknowledged that medical cannabis is being "increasingly used to treat various conditions" and that there is "difficulty in accessing these medicines" through official health bodies.

But despite the "poor quality" of the research, the NHS asserted that "there is currently not enough evidence" to support the use of medical cannabis to treat mental health conditions, as high-quality research is necessary first.

It revealed that there is evidence though that regular use of "street cannabis" can increase the risk of developing a psychotic illness such as schizophrenia.

Those suffering symptoms of depression, anxiety or any other mental health condition are advised to contact their GP who may be able to recommend "safe and effective psychological therapies and medicines" - which are available and backed by "strong evidence."