Cannabis: menace or medicine?

Latex gloves, white lab coat and an expression of intense concentration. This is not your stereotypical image of a cannabis user, but it is one. Scientific researchers from all over the globe are devoting their time to uncovering the secrets of cannabis. If you are able to believe the hype, cannabis can relieve pain, prevent infection by HIV and fight cancer. In the UK, the first medicinal license for a cannabis-based medicine, Sativex, was granted in 2010, yet cannabis remains an illegal substance. So, is it medicine or menace?

The human body regulates appetite, pain, mood and memory by using small chemicals as messengers. Like we use language to communicate, the body uses chemicals to talk. It just happens that the cannabis plant produces hundreds of substances that are very similar in structure to the body’s own messengers. These alien messengers can infiltrate the system; this is why some cannabis users experience ‘The Giggles’, ‘The Munchies’ and feelings of relaxation. Scientists are trying to exploit this infiltration of the messenger system to correct problems in the human body. Research on the vast numbers of these compounds produced by the cannabis plant (collectively called cannabinoids) is still in its infancy, but the future looks promising. Sativex is the first cannabis-based licensed drug, and it has been proven through extensive clinical trials to ease the pain and muscle problems associated with Multiple Sclerosis (MS) and cancer pain. All the benefits scientific researchers are alluding to cannot be accessed by simply smoking a joint; the messengers need to be extracted, isolated and their levels controlled; just as the same words mean different things in different sentences.

But cannabis in its recreational form has a dark side; psychosis, schizophrenia and depression have all been associated with its use. How can we ensure that cannabis as a medicine will not cause these detrimental effects? At the moment, the level of risk cannabis presents has not been clearly established. As part of the CafĂ© Controversial series in Aberdeen, Professor Ruth Ross from the University of Aberdeen compared the link between cannabis and mental illness to that between smoking and lung cancer: “It is a well-established fact now that smoking is linked to lung cancer. However, this view took many years and extensive research was required to prove the link as not all smokers develop lung cancer.” Long-term, large-scale studies are needed to prove this link and there are a number of reasons why it is difficult to make conclusions from older studies on cannabis use. Firstly, mental health issues do not show up on an X-ray like a tumour. Categorisation and diagnosis of mental illness is extremely complex, which makes data difficult to gather, analyse and quantify. Secondly, if you smoke cannabis and then develop a mental health problem, it does not necessarily follow that cannabis is the cause. A famous study of 50,000 Swedish conscripts noted that smoking cannabis at the age of conscription doubled the risk of schizophrenia in the ensuing 15 years. Another study showed that 10% of those who had used cannabis between the ages of 15 and 18 were diagnosed with schizophrenia at the age 26, compared to 3% who had not. Studies like these highlight an association between cannabis use at a young age and schizophrenia, but this correlation does not imply cause and effect. The situation is more complex, as this quote in The Times from Dr Paddy Power, consultant psychiatrist at Lambeth Hospital explains:

“It would be wrong to say that cannabis alone causes psychosis, It’s a bit like saying someone had a heart attack because of a stressful incident when they also ate too much fatty food, took too little exercise and smoked. In much the same way, using cannabis can be a major contributory factor in the onset of psychosis.”

Another complicating factor is the type of cannabis available. Recent research has suggested that one particular substance produced by cannabis, cannabidiol (CBD), can act as an antipsychotic and could even be used to treat schizophrenia. The active ingredient in Sativex is tetrahydrocannabidol (THC); it is responsible for the “high” experienced by recreational users of cannabis. But Sativex contains a tightly regulated ratio of THC to CBD. In recreational cannabis, the levels of THC and CBD is not controlled. It is known that one form of recreational cannabis, ‘skunk’, contains very little CBD. However, much of the research available to date does not take these ratios or levels into account, making it difficult to determine what is responsible for the detrimental effects.

What is clear is that cannabis as a medicine needs to be separated from cannabis as a recreational drug. The individual messengers need to be investigated in more detail and only through further research will we be able to decipher the language of cannabis, both good and bad.
I wrote this for the first issue of Au Science Magazine (you can read the whole magazine online).


  1. This is an excellent article, generally accurate although the information about THC/CBD ratios is incorrect. Cannabis connoisseurs select different strains to grow and enjoy with different ratios, and it is not just the 100+ cannabinoids but also the flavonoids and terpines, all of which impact on the effect and experience.

    It is directly comparable to choosing a bottle of wine.

  2. Yes, very true. I wanted to highlight the role of CBD as a possible antipsychotic and that there are strains available without any CBD. I should have added in that there are a whole world of variations in between.

  3. This whole misconception of 'Skunk' needs to end. All it is is the same plant grown with actual care, genetics do of course play a large role in this.
    I am by no means against cannabis being medicalised this way but to discredit cannabis' medicinal benefits in a smoked joint would be inaccurate. This practice is what has lead to the findings. The right to self titrate and growing for any adult should undoubtably be allowed reguardless of the medical potential of this plant.

    Smoking a joint with 400ml of cannabinoid in it will deliver approximately 4ml of cannabinoid inhaled. Thats about 1ml short of of Sativex squirt. You can use Sativex till you feel relief just like you can smoke joint till you feel relief.

    Bedrocan BV offer THC:CBD strains 19:>1, 12:>1 as well as Bediol which is a CBD rich cannabinoid.

    There also needs to be a distinction made between terpines and THC as the combination creates the Indica/Sativa effect which is more likely to be the contributing factor towards mood enhancement. Ethan Russo has done some excellent work on this.


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