Pubdate: Sat, 28 Oct 2017
Source: Victoria Times-Colonist (CN BC)
Copyright: 2017 Times Colonist
Author: Scott McLeod
Page: A12


Many Canadians can hardly wait for the day that the recreational use
of marijuana becomes legal. As a medical 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 out of the gate 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 might become more inclined to
self-medicate with this so-called "miracle drug."

Let's first look at the research on the medical use of

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 past 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.

Parents are considering such options because these medical conditions
do not always respond well to traditional prescription drug or therapy
options. Many have heard of "miracle cures" in the media from the use
of medical marijuana.

I wish I could be more positive when they ask. I find the possibility
of a new medicine to benefit conditions that don't respond well to
current medications exciting. Unfortunately, the research is not there
yet. So, what do we know so far? Here's the good news. In May of this
year, a double-blind placebo-controlled trial showed that cannabidiol
- - one of the active ingredients within the marijuana plant - 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 might even be approved for use in difficult-to-treat epilepsy
cases by the U.S. Federal Drug Administration, based on the latest

There's some other promising news: Medical 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 might 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 medical
marijuana might have short-term benefits, long-term use might result
in increased aggressive behaviour or even worsening of symptoms.

Today's medical 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 medical marijuana could bring medical
breakthroughs in the future, more needs to be done to inform the
public that it remains in experimental stages - and currently, for the
majority of conditions or ailments, it has minimal to no evidence of
benefit and might even be harmful.

Legalization will remove some red tape to allow for more research, but
many patients might choose to self-medicate without ongoing monitoring
of their symptoms, or they might choose to delay seeking help from a
medical professional. These are just some of the public-health
consequences that could come from the legalization of something that
many see as an all-purpose medical cure.

It's in everyone's best interests to try to set the record straight.

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Scott McLeod, MD, FRCPC, is a pediatrician practising in Calgary who 
specializes in the diagnosis and treatment of children with 
developmental disabilities, is and an expert with
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