UK cannabis market dominated by high-potency ‘skunk’
The first comprehensive survey of cannabis strength published in the UK for almost 10 years finds that high-potency varieties made up 94% of police seizures in 2016. The study, co-authored by King’s College London researchers, highlights the potential threat posed to mental health by a market dominated by strong cannabis.
Researchers analysed almost a thousand police seizures of cannabis from London, Kent, Derbyshire, Merseyside and Sussex. The same areas were last sampled in 2005 and 2008. In 2016, 94% of police seizures were high-potency sinsemilla, also known as ‘skunk’, compared to 85% in 2008 and 51% in 2005.
‘In previous research we have shown that regular users of high-potency cannabis carry the highest risk for psychotic disorders, compared to those who have never used cannabis,’ says senior author Dr Marta Di Forti, MRC Clinician Scientist at King’s College London’s Institute of Psychiatry, Psychology & Neuroscience.
‘The increase of high-potency cannabis on the streets poses a significant hazard to users’ mental health, and reduces their ability to choose more benign types,’ says Dr Di Forti.
The study, published today in the journal Drug Testing and Analysis, found the dominance of sinsemilla was mainly due to a sharp reduction in availability of weaker cannabis resin; from 43% in 2005 and 14% in 2008, to just 6% in 2016 but as low as 1% in the London area.
The average concentration of THC - the main psychoactive component of cannabis – in resin also increased from 4% to 6%. The average concentration of THC in sinsemilla has remained at 14% between 2005 and 2016.
Historically, cannabis resin has been rich in cannabidiol (CBD), which is almost entirely absent from sinsemilla. Due to its antipsychotic activity, CBD may potentially moderate some of the effects of THC. However, changes in the source of cannabis plants used for resin has led to a drop in CBD content. In 2005 and 2008, the ratio of THC to CBD was 1:1, whereas in 2016 the ratio was 3:1.
A recent King’s College London study found the first evidence for a relationship between increases in cannabis potency and first-time admissions to drug treatment, using data from the Netherlands. The research team are now investigating whether changes to the cannabis market in the UK are having a measurable impact on mental health.
Dr Di Forti, whose research into the mental health impacts of cannabis is funded by the Medical Research Council, says ‘More attention, effort and funding should be given to public education on the different types of street cannabis and their potential hazards. Public education is the most powerful tool to succeed in primary prevention, as the work done on tobacco use has proven.’
NOTES TO EDITORS
Paper reference
‘Potency of Δ9–tetrahydrocannabinol and other cannabinoids in cannabis in England in 2016: Implications for public health and pharmacology’, Potter et al, Drug Testing and Analysis, DOI: 10.1002/dta.2368
Contact
For a copy of the paper, to interview Dr Marta Di Forti or for further media information please contact: Robin Bisson, Senior Press Officer, Institute of Psychiatry, Psychology & Neuroscience, King’s College London, robin.bisson@kcl.ac.uk / +44 20 7848 5377 / +44 7718 697176.
About King’s College London kcl.ac.uk
King's College London is one of the top 25 universities in the world (2017/18 QS World University Rankings) and among the oldest in England. King's has more than 26,500 students (of whom nearly 10,400 are graduate students) from some 150 countries worldwide, and nearly 6,900 staff. The university is in the second phase of a £1 billion redevelopment programme which is transforming its estate.
King's has an outstanding reputation for world-class teaching and cutting-edge research. In the 2014 Research Excellence Framework (REF) King’s was ranked 6th nationally in the ‘power’ ranking, which takes into account both the quality and quantity of research activity, and 7th for quality according to Times Higher Education rankings. Eighty-four per cent of research at King’s was deemed ‘world-leading’ or ‘internationally excellent’ (3* and 4*). The university is in the top seven UK universities for research earnings and has an overall annual income of more than £600 million.
King's has a particularly distinguished reputation in the humanities, law, the sciences (including a wide range of health areas such as psychiatry, medicine, nursing and dentistry) and social sciences including international affairs. It has played a major role in many of the advances that have shaped modern life, such as the discovery of the structure of DNA and research that led to the development of radio, television, mobile phones and radar.
King's College London and Guy's and St Thomas', King's College Hospital and South London and Maudsley NHS Foundation Trusts are part of King's Health Partners. King's Health Partners Academic Health Sciences Centre (AHSC) is a pioneering global collaboration between one of the world's leading research-led universities and three of London's most successful NHS Foundation Trusts, including leading teaching hospitals and comprehensive mental health services. For more information, visit: kingshealthpartners.org.
About the Medical Research Council
The Medical Research Council is at the forefront of scientific discovery to improve human health. Founded in 1913 to tackle tuberculosis, the MRC now invests taxpayers’ money in some of the best medical research in the world across every area of health. Thirty-two MRC-funded researchers have won Nobel prizes in a wide range of disciplines, and MRC scientists have been behind such diverse discoveries as vitamins, the structure of DNA and the link between smoking and cancer, as well as achievements such as pioneering the use of randomised controlled trials, the invention of MRI scanning, and the development of a group of antibodies used in the making of some of the most successful drugs ever developed. Today, MRC-funded scientists tackle some of the greatest health problems facing humanity in the 21st century, from the rising tide of chronic diseases associated with ageing to the threats posed by rapidly mutating micro-organisms. www.mrc.ac.uk
Robin Bisson
Senior Press Officer
Institute of Psychiatry, Psychology & Neuroscience, King's College London
@KingsIoPPN
