Pubdate: Thu, 09 Nov 2017
Source: Sun Times, The (Owen Sound, CN ON)
Copyright: 2017 Owen Sound Sun Times
Author: Scott McLeod
Page: A4


Many Canadians can hardly wait for the day that the recreational use
of marijuana becomes legal. As a doctor, I'm far less enthusiastic. I
worry about two things: the experimental nature of marijuana in
medical practice, and the public health consequences of legalized marijuana.

Before you write me off as overly prudish or an anti-marijuana
conservative, let me say that I'm not opposed to legalized marijuana
in principle. I'm just paying attention to the evidence, or rather,
the lack of it. My concern is that as marijuana becomes more easily
available, Canadians may become more inclined to self-medicate with
this drug.

I am frequently asked about medical marijuana in my pediatric practice
by caring parents who want to help their children with
difficult-to-treat conditions. Over the last few months, parents have
asked me if medical marijuana can be used to treat their child's
attention deficit hyperactivity disorder, autism spectrum disorder, or
cerebral palsy, for example.

Here's the good news. In May, a double-blind placebo-controlled trial
showed that cannabidiol - one of the active ingredients in marijuana -
reduced the number of seizures in children with Dravet syndrome, a
condition that results in severe seizures, developmental delays and
problems with movement and balance.

The drug may even be approved for use in difficult-to-treat epilepsy
cases by the U.S. Federal Drug Administration.

There's some other promising news: marijuana has also shown a moderate
degree of benefit for patients with neuropathic pain and stiffness and
involuntary muscle spasms related to multiple sclerosis.

Other uses, such as the treatment of nausea and vomiting following
chemotherapy for those with cancer; assistance with improving weight
gain in HIV patients; improvement in sleep disorders and the reduction
of the symptoms of Tourette syndrome all have less evidence of
benefit, but may be promising for some in the future.

But that's where the research ends.

Some of the popularized ways in which medical marijuana is currently
being used, such as for post-traumatic stress disorder and anxiety,
lack long-term evaluation. While marijuana may have short-term
benefits, long-term use may result in increased aggressive behaviours
or even worsening of symptoms.

Today's marijuana is also not what it once was. Generally, we've seen
a consistent increase in the THC content of marijuana - the main
psychoactive component - from the 1960s to the present day. In fact,
THC is being sold by licensed producers at concentrations of greater
than 15 per cent in a substantial proportion of available strains.

Why is this a problem? The cannabis used in medical research contains
less than 10 per cent THC. We do know that using cannabis with higher
THC concentrations is associated with an increased risk of psychosis,
but we really don't know much about the medical effects at these
higher concentrations.

While I remain hopeful that marijuana may bring medical breakthroughs
in the future, more needs to be done to inform the public that medical
marijuana remains in experimental stages and that currently, for the
majority of conditions or ailments, it has minimal to no evidence of
benefit, and may even be harmful.
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