What we know about marijuana
by Margret Kopala

Published in the Ottawa Citizen, May 31, 2008

Leading the National Post debate on cannabis, columnist Barbara Kay can’t have anticipated that Vancouver’s safe injection site rather than legalized cannabis would be the Trojan Horse for the legalization of all addictive drugs.

This week, the right of addicts to continue use of illicit drugs was upheld by the B.C. Supreme Court even though no treatment of which I am aware uses the substance that caused the problem to cure it. Smokers use nicotine gum, not more cigarettes, to kick the habit, don’t steal to feed their habit and if heroine and cocaine are so helpful, why aren’t doctors prescribing them in pill form?

At least we know something about this substance. In fact we know a lot. And now a paper published in Nature places the medicinal, the harmful and the recreational aspects of cannabis in a perspective that has implications for how we treat all addictive substances.

Readers of this column will be aware of research in the United Kingdom where, according to The Independent, of an estimated 500,000 cannabis addicts, some 26,000 sought treatment in 2006. Here, Europe’s largest psychiatric research facility, London University’s Institute of Psychiatry, has been at the cutting edge of findings that establish a clear connection between cannabis use and psychosis. Though no user is immune, vulnerable adolescents are at particular risk for developing schizophrenia, a progressively disabling form of psychosis producing, as one British psychiatrist describes it, hallucinations, delusions and bizarre behaviour, in young adulthood.

New research from the Institute using MRI scans demonstrates how two active ingredients in cannabis affect the brain. The first called cannabidiol (CBD) relaxes it while the other creates temporary hallucinations and feelings of paranoia. Tetrahydrocannabinol (THC), we now know, switches off a regulator in the inferior frontal cortex by disrupting neuronal signaling.

“Cannabis, the mind and society: the hash realities” synthesizes these and other findings. Lead author and the Institute’s authority on marijuana and psychosis, Robin M. Murray, confirmed to me by email that it remains the most current on the subject.

It is also the most important. Not only does it provide much needed perspective, it also demonstrates how, irrespective of the number of individual peer reviewed studies, each with inherent limitations, no full understanding of a subject is possible without the contextualization that meta-analyses and overviews provide. Health Canada’s advisory committee on Insite, for instance, showed how such limitations led to a lukewarm endorsement of the facility.

If brain function is affected by CBD and THC, “Hash Realities” considers how causality is further suggested by the fact psychotic symptoms worsen with continued use (CBD masks the effects of THC) and how while family history is a factor, so are genes and a quarter of the population has them. And while cannabis is addictive and its use commonly precedes the use of hard drugs, the ‘gateway’ theory, formerly discredited, is now being scientifically verified.

The paper also references the past and exposes the confusions of the present. “The classical Greek term pharmakon indicates that a substance can be a remedy as well as a poison,” it says. Cannabis based medicines have a future but, in a “rational world”, these would not be influenced by attitudes towards recreational use where real problems do exist. Most problematic? Four per cent of the global population uses cannabis; world production has doubled since the early 1990s and THC concentrations have escalated. The number of children using the drug is rising. By 2010, one study predicts, “a substantial increase in the incidence of schizophrenia should be apparent.” Legalized cannabis presented few problems in the Netherlands (where because of recent findings the policy is now being reconsidered, but highly restrictive Sweden presented fewer problems still.

Murray et al do not consider Canada specifically but here the picture they present is complicated by the fact marijuana use is the highest in the industrial world. Its user – yes, users including children and weekend tokers – its user, grow and export operations, worth 6 billion dollars in British Columbia alone, finance the import of guns and hard drugs whose victims land in Canada’s urban centres where health communities then seek desperate solutions such as Insite.

“Hash Realities” concludes that public education is more effective than legislation but given the evidence, the British government recently made cannabis possession punishable by up to five years in prison.

Now where are the comparable perspectives on heroine and cocaine use?

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