Our research with Cannabis

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.

About Cannabis and Cannabinoids

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.

“Marijuana is one of the least toxic substances in the whole pharmacopoeia”
Professor Lester Grinspoon, Harvard Medical School, USA

“The illegality of cannabis is outrageous, an impediment to full utilization of a drug which helps produce the serenity and insight, sensitivity and fellowship so desperately needed in this increasingly mad and dangerous world"
Carl Sagan

Our publications on cannabis

Cannabis Policy: Moving Beyond Stalemate

Professors Robin Room, Peter Reuter, Wayne Hall, Benedikt Fischer, and Simon Lenton, 2010

Read more

Roadmaps to Regulation: Cannabis, Psychedelics, MDMA, and NPS

Amanda Feilding (Coordinating Editor) and Nicola Singleton, with additional input from Alex Stevens, 2016

Read more

Políticas Sobre el Cannabis

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

Read more

Cannabis and the Psychedelics: Reviewing the UN Drug Conventions

Prohibition, Religious Freedom, and Human Rights: Regulating Traditional Drug Use, 2013

Read more

Cannabidiol inhibits THC-elicited paranoid symptoms and hippocampal-dependent memory impairment.

Journal of Psychopharmacology, 2013

Read more

Communication breakdown: delta-9 tetrahydrocannabinol effects on pre-speech neural coherence

Molecular psychiatry, 2012

Read more

Investigating the interaction between schizotypy, divergent thinking and cannabis use

Consciousness and cognition, 2012

Read more

Does intravenous Δ9-tetrahydrocannabinol increase dopamine release? A SPET study

 Journal of psychopharmacology, 2011

Read more

Disruption of Frontal Theta Coherence by Δ9-Tetrahydrocannabinol is Associated with Positive Psychotic Symptoms

Neuropsychopharmacology, 2011

Read more

Delta-9-tetrahydrocannabinol disruption of time perception and of self-timed actions

Pharmacopsychiatry, 2010

Read more

Opposite Effects of Δ-9-Tetrahydrocannabinol and Cannabidiol on Human Brain Function and Psychopathology

Neuropsychopharmacology, 2010

Read more

Briefing paper: An Overview of Cannabis Policy: Moving Beyond Stalemate

Dave Bewley-Taylor and Chris Hallam, October 2008

Read more

Report of the Global Cannabis Commission

Robin Room, Wayne Hall, Peter Reuter, Benedikt Fischer, and Simon Lenton. Convened by Amanda Feilding, 2008

Read more

Cannabis and Mental Health Responses to the Emerging Evidence

Neil Hunt, Simon Lenton, John Witton, April 2006

Read more

Briefing Paper: Reclassification of Cannabis in the United Kingdom

Mike Trace, Axel Klein, Marcus Roberts, May 2004

Read more