Cannabidiol: A novel treatment for cannabis dependence?
Team: Professor Val Curran, Dr Tom Freeman, Chandni Hindocha, Natacha Shaban, Emily Thomas and Dani Astbury
Collaborators: Professor Celia Morgan (University of Exeter)
In Europe, 1% of all adults and nearly 2% of 14-17 year olds are addicted to cannabis. Rates of cannabis dependence have increased markedly over recent years alongside changes in the ingredients of cannabis available on the market (increasing skunk or sinsemilla with high THC and lacking CBD). Among UK first-time drug treatment clients, cannabis is now the primary addiction in 28% of those entering drug treatment, second only to heroin (41%). At present, clinicians rely on psychological treatments which have very limited effectiveness. There is no pharmacological treatment for cannabis addiction. If we found a safe, effective medicine this could improve treatment in a similar way that various medicines have improved rates of stopping tobacco use. It would also impact on educational/vocational achievement and illegal behaviour, and reduce young people's risks of cannabis-associated mental health problems (e.g. schizophrenia, depression).
Converging preclinical and human research suggests cannabidiol (CBD) to be a highly promising treatment, with excellent tolerability and safety. One of the key withdrawal effects of cannabis is anxiety and CBD reduces anxiety. CBD has shown promising pro-cognitive and neuroprotective effects which may reverse some of the cognitive deficits associated with cannabis dependence that are a barrier to the effectiveness of psychotherapies. Our recent research has shown that cannabis dependence is more common in those using 'skunk' - a type of cannabis containing high THC levels but little, if any, CBD. Other data suggest a mechanism by which CBD may be protective against cannabis dependence. A key feature of addiction is that an addict's attention is strongly drawn to cues related to the drug abused over and above other cues and this makes it hard to stop use. Animal evidence suggests that CBD can reduce the ability of drug cues to cause relapse to heroin. In people dependent on cannabis, we have found that CBD reduced attention grabbing by cannabis-related pictures. After CBD, cannabis users rated cannabis pictures as less pleasurable. Thus CBD may reduce the motivating power of drug cues. Overall, evidence now suggests that CBD is a logical treatment for cannabis dependence, by targeting key mechanisms both in dependence and equally importantly, cannabis withdrawal symptoms.
This project's objectives are first to determine the optimal dose of CBD and then evaluate its efficacy in treating cannabis dependence.
This project was funded by the UK Medical Research Council