Opinion: Beliefs about the miraculous medicinal benefits of marijuana are misguided
False health claims for cannabis are often a Trojan horse to decriminalise cannabis for purely recreational use
Cannabis
has been used for both recreational and medicinal reasons for
millenniums, and in February the Dáil voted to legalise it for specific
medical conditions. This has been contested by People Before Profit,
which claims cannabis is hugely beneficial for a much wider array of
illnesses, and accordingly demands wider access. This position is
buttressed by gushing testimony of the nigh-on-miraculous powers of
cannabis. Yet stripped of emotive rhetoric, such claims are incredibly
suspect – and inadvertently dangerous.
Contrary to the perception that it
has been neglected by the medical profession, in reality cannabinoids
have been studied for decades. Far from being understudied, there have
been more than 10,000 peer-reviewed investigations into potential
medicinal applications of cannabis, and it is already in clinical
practice. Its antiemetic properties have been exploited since the 1980s
in a number of common medicines, including dronabinol and nabilone, to
treat nausea induced by chemotherapy.
In stark contrast to the claims of
medicinal cancer advocates, research suggests the potential benefits
are relatively modest. A comprehensive review published this year by the
National Academies of Sciences, Engineering and Medicine examined all
evidence to date. Conclusion: despite the abundance of investigations
into medical use of cannabis, there was evidence to support only three
therapeutic uses – treating nausea, chronic pain and reducing spasms in
multiple sclerosis.
These aren’t negligible, but this
modest contribution must be seen in context. Crucially, the scientific
literature simply doesn’t support its use for the many conditions it is
alleged to improve, and clinical investigations have shown no
demonstrable efficacy for treating ADHD, weight loss in Aids patients,
or for epilepsy or autism.
Side effects
Even for conditions where
cannabinoids have application, side effects can be severe and often
render it of limited use. THC is not uniformly well-tolerated, and can
paradoxically make vomiting worse in many patients. As safer and more
effective alternatives exist, THC-based medications are generally only
employed when other approaches fail.
Nothing more starkly illustrates
the disconnect between the hyperbolic promises and underwhelming
evidence than claims made regarding cannabis and cancer. The
alliterative mantra “cannabis cures cancer” is ubiquitous among
proponents of medicinal marijuana. Such claims are illustrated by
miraculous testimonials, from stories of tumours disappearing with
cannabis oil to parents “curing” their child’s paediatric cancer with
cannabis. These anecdotes are shared relentlessly online, proffered with
zero scepticism.
The Irish campaign has been no
exception, with such accounts shared widely. Proponents of the Bill,
such as People Before Profit TD Gino Kenny, have endorsed pages of such
testimony on social media, and speakers at public gatherings (such as
the recent Right to Water rally) have taken a similar proposition.
These claims are, to be blunt,
absolutely wrong-headed and completely irresponsible. There is zero
evidence that cannabis alleviates cancer of any type, and in human
trials cannabis has shown no anti-cancer properties.
Vocal proponents vapidly clutch at
studies that suggest high doses of cannabis-derived products can kill
cancer cells in petri dishes. This is true, but their miracle-cure
inference betrays a deep misunderstanding. THC can kill cancer cells in a
dish, but so can acid, bleach and heat. Killing cells is trivial –
effective anti-cancer agents must differentially destroy cancer cells
over healthy cells.
For cannabis, there is no evidence to suggest this is the case – and no amount of special pleading circumvents this reality.
For cannabis, there is no evidence to suggest this is the case – and no amount of special pleading circumvents this reality.
Scientific evidence
Still, advocates appear
uninterested in scientific evidence, persisting with unsupported claims.
These myths are dogma, not reality. When challenged, proponents resort
to conspiratorial mumblings to explain away the lack of evidence for
their assertions.
Typically this manifests in the
accusation that Big Pharma is suppressing awareness of the curative
powers of cannabis. Under this narrative healthcare professionals and
scientists are rendered as de-facto villains, nefarious agents of
disinformation whose pleas for evidence-based policy can be dismissed
with prejudice and without consideration.
This is cynically self-insulating,
turning those pushing for evidence-based policy into targets of abuse.
This can be seen in the vitriol unleashed on Fine Gael TD Kate O’Connell
for questioning misleading testimony over medicinal cannabis.
Tellingly, O’Connell’s
qualification in pharmacology is taken not as a signifier of expertise
but rather as grounds to dismiss her as a “vested interest”. Autism
rights campaigner Fiona O’Leary has endured similar abuse for pointing
out the lack of evidence for cannabis-based autism “cures”.
Wild promises
As a cancer researcher and science
writer, I too have been on the receiving end of such accusations. While
it’s always unpleasant to be targeted for abuse or to have one’s
motivations questioned, this hostility against evidence has a much more
dangerous consequence.
By encouraging a mistrust of the
medical profession and pushing unsubstantiated cures, there is a very
real danger that patients abandon conventional medicine for the wild
promises of the cannabis lobby. Abandoning effective treatments to chase
false hope happens with depressing frequency.
Those endorsing false claims bear much of the responsibility for these tragic outcomes.
Those endorsing false claims bear much of the responsibility for these tragic outcomes.
All this aside, the current
campaign has a glaring double standard at its core. While the HPRA
recommended the prescription of cannabis for certain conditions, this
has been rejected by proponents of the Medicinal Cannabis Bill, who want
unfettered access. This stance completely undermines the pretence that
medicine is the aim – all medications have side effects, and cannabis is
no exception. These are typically mild, but also include strong
association with some forms of psychosis.
Arguments that cannabis is
“natural” and should be exempt from regulation are equally hollow –
uranium and arsenic also occur naturally, but we still regulate their
possession for good reason. Like any drug, doses must be carefully
controlled. If medicinal use is the true aim, then it should be subject
to the HPRA regulation.
That proponents reject this is
telling of a different motivation. For all the ostensible concern over
medical access, this appears to be little more than a Trojan horse to
decriminalise cannabis for conventional recreational use. And while
there are excellent arguments for legalisation, it is completely
unacceptable to make dangerously misleading medical claims to this end.
Whatever the intention, there is
no excuse for propagating health fictions. Such falsehoods are damaging
to public understanding of science and medicine, and ultimately, put
lives at risk.
