One of our earliest collaborations, formed in 2007 with Dr Paul Morrison at King’s College London, investigated the effects of cannabidiol (CBD) on the brain, as well as its relationship to THC. Specific topics included the neuroprotective potential of CBD, the pro-psychotic effects of THC and the ability of CBD to block them, and altered time perception after THC. The studies were among the first to explore CBD’s anti-anxiety and anti-psychotic properties, and some of the earliest studies into how cannabis-related harms can be reduced by ensuring a balanced THC/CBD ratio.
In collaboration with Prof Val Curran at University College London, we are now using brain imaging to compare the effects of two different strains of cannabis – one with high THC content and minimal CBD, and the other with a balanced CBD/THC ratio – on cerebral circulation and brain function. This study was featured in the Channel 4 documentary Drugs Live: The Cannabis Trial, which aired in March 2015. The research demonstrates that high-THC cannabis impairs certain brain networks, while CBD helps counteract some of these negative effects. These findings are important for developing harm reduction strategies, given that in the UK, 80% of the cannabis sold is high-THC.
In collaboration with Prof Celia Morgan, at the time at University College London, we also conducted a study on cannabis and creativity, and a study with Harborside Health Centre investigating the efficacy of different strains of cannabis (with particular attention to the THC/CBD ratio) in the treatment of illnesses. With Prof Morgan now at Exeter University, we are currently designing a study to test the efficacy of CBD for smoking cessation.
Finally, we are involved in an exciting new clinical trial, led by Drs Manuel Guzman and Guillermo Velasco at Madrid Complutense University, investigating the anti-cancer properties of cannabis and individual cannabinoids, which have been found to exhibit anti-tumour effects in animal models and in vitro studies of cancer. We are now preparing a clinical trial across sites in Spain to test whether cannabinoids can help fight brain tumour growth in cancer patients. The study will include an MRI brain imaging component.
Humanity’s history with cannabis reaches back to the dawn of civilization. Cannabis has long been valued for its long-lasting and strong fibre, its nutritious and oil-rich seeds, and its psychoactive and medicinal properties. The first medical applications, for over 100 ailments, are attributed to the legendary Chinese Emperor Shen Nung who lived around 2700 BC. It is the most popular illegal recreational drug in the UK, and it constitutes roughly 80% of the illegal drug market. Cannabis is controlled by the 1961 UN Single Convention on Narcotic Drugs, which means that it is illegal under international law for any country to legalise the commercial sale of cannabis, although many countries and US States have decriminalised or legalised possession or trade.
Cannabis has a very complex and diverse chemical composition – the total number of constituents identified in cannabis so far is 545. 104 of these compounds are cannabinoids (defined as chemicals that can interact with the brain’s ‘endocannabinoid’ system). The endocannabinoid system includes two types of cannabinoid receptors: CB1 and CB2. CB1 is found mainly in the brain, while CB2 is found mainly in the immune system. The most well-known cannabinoid is THC (Delta-9-tetrahydrocannabinol), the main psychoactive component responsible for the ‘high.’ THC primarily binds to the CB1 receptor, but stays bound longer than the brain chemical the receptor was intended for (‘anandamide’), which is why THC is psychoactive and anandamide is not. Another cannabinoid that has recently gained attention is cannabidiol or CBD. Hundreds of other, non-cannabinoid components have also been identified in/isolated from cannabis. Some of these compounds belong to the terpenoid class, and some are flavonoids.
Professors Robin Room, Peter Reuter, Wayne Hall, Benedikt Fischer, and Simon Lenton, 2010
Amanda Feilding (Coordinating Editor) and Nicola Singleton, with additional input from Alex Stevens, 2016
Robin Room, Benedikt Fisher, Wayne Hall, Simon Lenton, Peter Reuter, Diana Rossi, Raúl Alejandro Corda (Authors), Manuel Casals (Translator), Amanda Feilding, Thomas C Schelling (Contributors), 2014
Prohibition, Religious Freedom, and Human Rights: Regulating Traditional Drug Use, 2013
Journal of Psychopharmacology, 2013
Molecular psychiatry, 2012
Consciousness and cognition, 2012
Journal of psychopharmacology, 2011
Dave Bewley-Taylor and Chris Hallam, October 2008
Robin Room, Wayne Hall, Peter Reuter, Benedikt Fischer, and Simon Lenton. Convened by Amanda Feilding, 2008
Neil Hunt, Simon Lenton, John Witton, April 2006
Mike Trace, Axel Klein, Marcus Roberts, May 2004
Psilocybin for Depression
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