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14 May 2018

BY PROFESSOR STEPHEN LEEDER, EMERITUS PROFESSOR PUBLIC HEALTH, UNIVERSITY OF SYDNEY

Cannabis has a long history, as writer Agata Blaszczak-Boxe tells it in a 2017 Live Science article.

“From the sites where prehistoric hunters and gatherers lived, to ancient China and Viking ships, cannabis has been used across the world for ages … The history of cannabis use goes back as far as 12,000 years, which places the plant among humanity's oldest cultivated crops … Burned cannabis seeds have been found in kurgan burial mounds in Siberia dating back to 3,000 B.C., and tombs of noble people buried in Xinjiang region of China and Siberia around 2500 B.C. have included large quantities of mummified psychoactive marijuana.” 

Her article examines a report on the history of cannabis by Bernie Warf, a professor of geography at the University of Kansas in Lawrence: “For the most part, it was widely used for medicine and spiritual purposes during pre-modern times. For example, the Vikings and medieval Germans used cannabis for relieving pain during childbirth and for toothaches.”

This helps put the current discussion about the legal use of cannabis in context.

Blaszczak-Boxe’s article reminds us (as Warf points out) that there are two types of cannabis: “There is Cannabis sativa, known as marijuana that has psychoactive properties. The other plant is Cannabis sativa L. (The L was included in the name in honour of the botanist Carl Linnaeus.) This subspecies is known as hemp; it is a non-psychoactive form of cannabis, and is used in manufacturing products such as oil, cloth and fuel.” She also draws attention to a second psychoactive type of cannabis Cannabis indica that was identified by the French naturalist Jean-Baptiste Lamarck.

Blaszczak-Boxe notes that: “Both hemp and psychoactive marijuana were used widely in ancient China. The first record of the drug's medicinal use dates to 4000 B.C. The herb was used, for instance, as an anaesthetic during surgery, and … by the Chinese Emperor Shen Nung in 2737 B.C.”

Cannabis came to the Middle East with the development of east-to-west trade routes, brilliantly and engagingly described in Peter Francopan’s The Silk Roads, about 2000 years B.C., and from there to Europe. Warf said: “Cannabis seeds have also been found in the remains of Viking ships dating to the mid-ninth century”.

Cannabis arrived in the US in the early 20th century.  American attitudes to cannabis were formed, it is said, by Mexicans fleeing the Mexican Revolution who were: “Frequently blamed for smoking marijuana, property crimes, seducing children and engaging in murderous sprees.” By 1937 it was a criminal offence in all the US to possess marijuana.

With such a history, it is hardly surprising that it is difficult to arrive at an un-conflicted position about marijuana in our society. But its history surely supports therapeutic trials for pain relief. Recreational use remains contested territory. It is difficult to separate the pharmacological effects of serious use of cannabis from the sociological consequences that follow from using an illegal substance. 

A quick trawl through websites relating to marijuana confirms this ambiguity.  For example, a US site called AddictionCentre states: “The psychological consequences of prolonged marijuana abuse aren’t completely understood. Some studies suggest that marijuana addiction may increase the chances of developing mental disorders such as depression, anxiety, motivational disorder and schizophrenia.” Heavy-handed law-n-order approaches risk lumping marijuana with other more dangerous drugs, creating rather than solving problems.

Encouragingly, trials underway in Australia may help clarify its medical role.  With $9 million from the NSW Government, three such trials in NSW aim to assess its ability to:

  1. Reduce seizures in children with severe treatment-resistant epilepsy, through a partnership with the Sydney Children’s Hospitals Network
  2. Improve appetite and appetite-related symptoms in adult palliative care patients with advanced cancer
  3. Prevent chemotherapy-induced nausea and vomiting in adult patients where standard treatments have proven ineffective.

There are other trials in Australia and internationally.  As well, pharmaceutical research continues to clarify the role of different chemicals in marihuana, the cannabinoids, including THC (delta-9 tetrahydrocannabinol) and CBD (cannabidiol).  Worries are expressed about a Big Pharma takeover. 

Both THC and CBD have the potential to relieve pain, and CBD also has anti-inflammatory properties. THC accounts for the highs of marihuana. A web-based cannabis support line states that CBD on the other hand has an anti-psychoactive and anti-psychotic effect, possibly even relieving anxiety.

Tensions exist between those who recommend plant cannabis rather than pharmaceutical cannabinoids. Only well-constructed trials can resolve these questions. It is encouraging that such trials are underway,

 

 


Published: 14 May 2018