Could Cannabis Be Used to Treat Psychosis?Sifting the Evidence by Dr Suzi Gage
Today is World Mental Health day.
Given the huge personal and societal burden that poor mental health has, we’re surprisingly bad at treating it. Most of the drug treatments that doctors currently prescribe were originally identified by chance, and many of them will work for some but not all individuals who are prescribed them. Counselling and other talking therapies are extremely time intensive and the already-over-stretched NHS can struggle to provide these to people who are seeking them.
As such, some researchers are turning to what might sound like an unusual place to look for new treatments – the world of recreational drugs. Actually it’s not necessarily that unusual, plenty of drugs that we might think of as recreational also have medical uses – ketamine is on the World Health Organisation’s list of essential medicines due to its anaesthetic properties, and morphine is an incredibly important pain medication.
But could cannabis be used to treat something like psychosis? This seems at first glance highly unlikely – a number of studies have found quite the opposite, that cannabis use might actually increase the risk of psychosis and even schizophrenia. But cannabis has a number of compounds within it, and these don’t all have the same effect. Delta-9 tetrahydrocannabinol – or THC as it’s more commonly known – is probably the most well researched cannabinoid of the several hundred that are found within the cannabis plant. THC seems to be the compound that gets people high, and randomised controlled studies have found that THC intoxication can mimic transient psychotic-like experiences, but in almost all cases these effects disappear once a person is no longer high.
More recently, researchers have started investigating another cannabinoid found within the cannabis plant – cannabidiol, or CBD. CBD doesn’t seem to have a psychoactive effect like THC does, but it does have some other really interesting properties. When individuals are given CBD before THC, the transient psychotic experiences that they have are dramatically reduced. CBD also seems to reduce the impact that THC intoxication can have on cognition.
This led some researchers to wonder – could CBD be used to help people with psychosis or schizophrenia. Earlier this year, a small scale exploratory trial attempting to investigate just this was published. 88 patients with schizophrenia were given either 1000mg of CBD or a placebo alongside their usual antipsychotic treatment, every day for 6 weeks. The patients recruited were those who were partially responsive to their current antipsychotic medication – around one-third of patients prescribed antipsychotics for schizophrenia will have a poor response to them.
The researchers measured a number of different outcomes, including a self-reported psychotic experiences measure, cognitive performance and ratings by the patient’s own clinician, who was also unaware whether the patient had received CBD or placebo (the trial was double blind, meaning neither patients nor researchers knew which patients were in which condition).
After 6 weeks, psychotic-like experiences were reduced to a greater degree in the patients given CBD compared to placebo. Not only that, but their clinicians rated this group as having improved more, and as having lower illness severity.
Clearly this is a very small scale study, and as such these results are intriguing but not really conclusive. The reduction in psychotic symptoms over the six weeks was small. At baseline patients had a score of 18, and this reduced to 14.8 by the end of the study. A ‘treatment response’ was defined as an improvement of at least 20% on this score – 12 out of the 42 participants given CBD were classed as responders (6 of the participants in the placebo condition also met this criteria). And these patients were not given CBD alone, they were still on their usual antipsychotic medication, so this study doesn’t tell us whether CBD alone would reduce psychotic experiences.
But it does provide tantalising evidence that should be followed up in a larger scale study. Importantly, there was no difference in rates of adverse events between CBD and placebo groups – the side effects from current antipsychotic medications can be extremely unpleasant; weight gain, sleepiness and slowness, sexual problems, muscle spasms, and in rarer cases bed wetting, seizures and vision problems. Because schizophrenia can be such a life changing illness, patients have to weigh up the risk of these side effects with their treatment – if a new medication could be identified that had fewer severe side-effects, this could hugely improve quality of life for patients.
Having said that, I’m not suggesting you should rush out and buy yourselves some CBD oil to improve your mental health. At present, the CBD you can buy in health shops is not regulated or monitored – a group of researchers from the Netherlands collected samples from 21 different CBD oils and compared their actual CBD content with what they reported on the label. Seven samples contained no CBD whatsoever, and nine further samples had orders of magnitude less CBD than they claimed. Studies haven’t been published looking at CBD in the UK, but it is sold and marketed as a food supplement rather than a medication, and so strict regulation of content doesn’t apply. But I’m glad that more and more research is underway looking at the impact of CBD on various outcomes, and I can’t wait to see larger scale investigations.
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Dr Suzi Gage is a a psychologist and epidemiologist lecturing in and researching recreational drugs and mental health at the University of Liverpool. Suzi is currently writing her first book, based on her award winning podcast of the same name, Say Why to Drugs. You can find her on Twitter at @soozaphone.
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