Cannabis - Friend or Foe?
By: Rachel Pitts-Tucker, Hospital Services Manager, Harrogate Clinic
Cannabis has featured largely in the media over recent months with much debate following the downgrading the drug from class B to class C. Many people are not fully aware of the differences between Class A, B and C drugs. In fact, all require a valid prescription and are not legally available as OTCs (over the counter medicines e.g paracetamol).
It has long been believed by many who work in the field of Psychiatry that cannabis might be a precipitating or causal factor for various psychiatric illnesses, particularly schizo-affective disorders. Several recent research papers now give strong support to this belief. When thinking about the "harm" that may be caused by a particular drug (and therefore under which classification in the current system it should be held), it is important to review not only the short term effects but also to consider dependence, risk of overdose, withdrawal effects and the longer term damage caused by prolonged drug use. We should also be aware that whilst the attention drawn to them by the media raised the profile of drugs like cannabis and Heroin, there are many other drugs in common use with the potential to cause either addiction or harmful side effects - including those bought over the counter!
In the case of cannabis, it is recognised that one of the primary reasons for use is the hallucinogenic properties, of varying degrees depending on the type of cannabis used. This ranges from a mild lifting of mood to marked hallucinations and changes of thought process. This has in some cases developed into a cannabis-induced psychotic disorder, a complaint separately classified under ICD10 (International Classification of Diseases) code F12.5. It has been debatable whether this psychotic tendency is due to a predisposition towards psychosis or, alternatively, it is simply a short-lived and completely reversible psychotic episode. Recent research [Arendt et al 2005] into a group of cannabis users who had suffered cannabis-induced psychotic disorder (with no previous traditional psychotic disorder) between 1994 and 1999 showed that nearly half of these subjects subsequently developed schizoaffective-spectrum disorders. The study also showed that males were more at risk than females and that, for both sexes, psychoses developed at a considerably earlier age than those in the comparison group. This is the first study to show that cannabis-induced psychoses, previously believed to show complete remission, are found in nearly 50% of cases to develop into more malignant schizoaffective disorders. It is not the only research of this nature and provides evidence for a much greater risk to persistent cannabis users, particularly those starting in their early teens.
Having identified the above, many people with chronic pain and neurological disorders, for many years have self-medicated with cannabis. There is now a wealth of research to support the selective use of some of the pharmacological properties of cannabis THC (Tetrahydrocannabinol). Some compounds are hallucinogenic, some are analgesic, some anti-emetic and some are antispasmodic i.e. if carefully selected and delivered they provide excellent pain relief for a variety of diseases. One of these cannabis derivatives is now licensed for use in Canada and extensive clinical trials are underway in the UK .
Sativex is a CB receptor agonist containing equal amounts of the two cannabinoids, THC and cannabidiol. It has been used successfully in a study of the treatment of pain in rheumatoid arthritis [Blake et al 2006]. A trial of Sativex has also been run at Cygnet Health Care's heroin detoxification centre, Detox 5, as the symptoms of opiate withdrawal, such as nausea, muscle spasm and pain, create an excellent model for the study of Sativex efficacy. The results of the Detox 5 trial are not currently known as this was a 'Doubleblind, placebo controlled trial' (Gold standard research) and is still undergoing data processing by the statisticians. We await the outcome with quiet excitement.
So then, as many self-medicators have proclaimed for years, the therapeutic value of cannabis is enormous. However, as has been suggested in several studies, the harmful long term effects of cannabis smoking are also very much in existence. It is vital that these are further investigated and the implications of downgrading the drug to Class C status fully realised.
