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Single dose of the cannabis compound CBD reduces psychotic symptoms by normalising brain activity

A single dose of a supplement derived from cannabis reduces psychotic symptoms, new research suggests.

When suspected psychosis patients are given just one dose of the compound cannabidiol (CBD), their symptoms, such as depression and anxiety, become less severe, a UK study found today.

MRI scans reveal CBD helps to ‘readjust brain activity to normal levels’, according to the researchers.

CBD does not contain any THC, which is the component of cannabis that makes users ‘high’ and has been linked to psychotic symptoms.

Medical cannabis is available on prescription in the UK after it was approved by the Government last July.

Marijuana is legal for medicinal purposes in 30 US states, including California, Florida and Ohio. Nine states permit the drug for recreational use.

A single dose of a supplement derived from cannabis reduces psychotic symptoms (stock)


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 strains of marijuana. 

THC is the psychoactive compound responsible for the euphoric, ‘high’ feeling often associated with marijuana.

THC interacts with CB1 receptors in the central nervous system and brain and creates the sensations of euphoria and anxiety. 

CBD does not fit these receptors well, and actually decreases the effects of THC, and is not psychoactive. 

CBD is thought to help reduce anxiety and inflammation. 

How the research was carried out 

The researchers, from King’s College London, analysed 33 young people who were experiencing distressing psychotic symptoms but had not been diagnosed with psychosis.

These individuals were compared against 19 healthy people.

A single dose of CBD was given to 16 of the suspected psychosis patients, with the remaining 17 receiving a placebo.

All of the participants were then studied in an MRI scanner while performing a memory task that engages three regions of the brain known to be involved in psychosis.

CBD could be an ‘ideal treatment’ 

Perhaps unsurprisingly, results suggest that the brain activity of a suspected psychosis patient is abnormal compared to that of a healthy person.

Yet, after a single CBD dose, these patients’ brain activity becomes less severe than those who were given a placebo. 

The researchers believe their findings could pave the way for new psychosis treatments.

Study author Dr Sagnik Bhattacharyya said: ‘The mainstay of current treatment for people with psychosis are drugs that were first discovered in the 1950s and unfortunately do not work for everyone.

‘Our results have started unravelling the brain mechanisms of a new drug that works in a completely different way to traditional anti-psychotics.’

On the back of their findings, published in the journal JAMA Psychiatry, the researchers are launching a large trial to investigate whether CBD could treat people at risk of developing psychosis, such as schizophrenia or bipolar disorder patients.

Dr Bhattacharyya added: ‘One of the main advantages of cannabidiol is that it is safe and seems to be very well tolerated, making it in some ways an ideal treatment. 

‘If successful, this trial will provide definitive proof of cannabidiol’s role as an antipsychotic treatment and pave the way for use in the clinic.’ 


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