In the past 40 years, the potency of cannabis has on average doubled
worldwide and there is evidence of a greater number of people seeking
help for cannabis use disorders in the United Kingdom, Europe, and United States of America.
As cannabis laws become liberalized in many countries, experts writing in The Lancet Psychiatry
argue that there is an urgent need to explore how cannabis use can be made safer.
‘With the rapidly changing political climate around cannabis, there is need to effectively reduce cannabis-related harms, and conduct more research to inform policy decisions.’
The authors say that policy makers and researchers should consider
regulating cannabis potency, reducing the use of tobacco (e.g. by using
vapourizers), and exploring how the chemical composition of cannabis
could be modified to reduce harm without altering the pleasurable
effects of the drug.
Despite prohibitive laws on possession and use of cannabis being
introduced in the 1960s, cannabis use has increased in most parts of the
world, suggesting the laws have had little effect on use and abuse.
Uruguay and a number of US states, including California, Oregon, Alaska,
Maine, Massachusetts, Washington, Nevada, and Colorado allow cannabis
to be sold for recreational purposes. Canada is set to legalize its
recreational use in 2017 and several European countries, including
Portugal, Spain and the Netherlands, have lessened or abolished
sanctions on possession and use.
The main active compounds found in cannabis are
delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD). High potency
cannabis is high in THC with low (or absent) levels of CBD. This variety
is commonly known as sinsemilla (Spanish meaning "without seed") or
sometimes "skunk". Recent evidence suggests that CBD may protect against
some of the detrimental effects of THC such as memory impairment and
Writing in a Personal View, the authors, from the Institute of
Psychiatry, Psychology and Neuroscience at King's College London and UCL
(UK), argue that the time has come to consider harm reduction in
First, the authors say more focus on the harms of tobacco is needed
since cannabis is frequently used with tobacco, particularly in Europe.
For instance, smoke-free vapourizers could help reduce the harmful
effects of smoke and avoid the highly addictive properties of tobacco.
Secondly, they say that in countries where cannabis is legalized,
the potency of cannabis could potentially be addressed. In parts of the
USA where cannabis is legalized, THC is not regulated and extremely
potent cannabis products (up to 75% THC) have gained popularity. Some
policy makers in the Netherlands and Uruguay have suggested introducing a
cap to limit THC content to 15% and more evidence is needed on the
effect of these measures. Alternative options might include taxing
cannabis according to THC content.
However, the authors argue that these strategies might not be
entirely successful, as cannabis users tend to prefer cannabis with a
relatively high THC content. Instead, they argue that increasing the
levels of CBD could reduce some of the harmful effects of cannabis,
without compromising the effects users seek. More research into the
harms posed by different levels of THC and CBD content is needed, and
this information could potentially contribute to guidelines on safer
cannabis use, similar to alcohol.
"Although most users will not develop problems from their cannabis
use, it is vital, especially now that cannabis is becoming increasingly
liberalised, that we explore alternative and innovative ways by which we
can reduce and mitigate cannabis related harms" says Dr Amir Englund,
lead author from King's College London.
"With the rapidly changing
political climate around cannabis, the demand to effectively reduce
cannabis-related harms has never been greater, and more research is
urgently needed to inform policy decisions. A strategy based on
increasing the content of CBD in cannabis might be especially promising
because CBD can offset several harms associated with cannabis without
compromising its rewarding effects."
Dr Tom Freeman, a co-author and Senior Research Fellow for the
Society for the Study of Addiction said: "In the last eight years, the
number of people in the UK entering specialist treatment for cannabis
increased by over 50%. During the same time period, street cannabis has
become increasingly strong with high levels of THC and little or no CBD.
Further research on CBD is now needed - both to investigate its
potential role in mitigating the harmful effects of THC in cannabis, but
also as a potential treatment for the minority of people who develop
problematic cannabis use. Efforts to reduce the common practice of
mixing cannabis with tobacco could potentially prevent people
progressing to nicotine dependence, providing a substantial benefit for