Marijuana as Medicine
Consumer Reports, © Consumers Union, May 1997
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Should marijuana be used as a medicine, as its advocates say? Or
is it a dangerous drug of abuse that exposes users to brain
damage and lung cancer?
Last fall, voters in California and Arizona approved laws
allowing patients to smoke marijuana for medical purposes with a
doctor's recommendation. Other states are considering similar
moves. And the influential New England Journal of Medicine has
editorialized in favor of extending this policy nationwide.
Federal health and drug-enforcement officials have reacted
strongly to these initiatives. "Seeming to legalize marijuana for
anything would give young people the wrong impression," says
Sheryl Massaro, a spokeswoman for the National Institute on Drug
Abuse. "That doesn't even seem to enter the minds of a lot of
people who are promoting it for medical use."
The debate over medical marijuana seems likely to continue for
some time, caught up as it is in the larger question of how the
nation should deal with recreational drug use and abuse. "It's a
shame" that the debate is so polarized, says Harrison Pope, a
Harvard University psychiatrist who studies marijuana. "Science
should know more about this substance by now, considering how
long it has been in use." While the debate continues, here is
what is known about the health effects, both good and ill, of
this controversial drug.
The Harm It Can Cause
When it comes to the possible ill effects of chronic marijuana
use, the federal government has willingly funded studies and even
provided government-grown marijuana. The possible damage falls
into two categories.
Effects on the brain. Perhaps no aspect of marijuana use has been
so thoroughly studied. Researchers have established what many
users know: Marijuana's effects on coordination and short-term
memory make it inadvisable to drive, operate heavy machinery or
try to learn anything important while under the drug's influence.
The biochemical explanation for this may have come in 1988, when
scientists found receptors for THC, a marijuana component, in the
parts of the brain controlling memory, mood, visual processing,
attentiveness and the ability to filter out extraneous stimuli.
The discovery also clarified why it's impossible to take a fatal
dose of marijuana: There are hardly any THC receptors in the
areas of the brain that control basic life functions, such as
consciousness and respiration.
As for long-term effects of pot-smoking, the results are not
clear. Researchers have shown that daily users, after several
days of abstinence, continue to show subtle but measurable
cognitive impairments. But it's not clear whether this after-the-
fact impairment results from changes in the brain or is just a
slow, continuous release of marijuana constituents that have been
stored in the brain and fatty tissues. "Of the three studies of
this question that have been done, the results show no, mild, and
fairly pronounced long-term damage," says Pope. "So the jury is
still completely split." Also uncertain is whether marijuana
produces any withdrawal symptoms the way heroin, cocaine, alcohol
and nicotine do. The most that researchers have been able to
discern are occasional cases of mild and short-lived anxiety and
insomnia upon abrupt cessation after years of heavy use.
Respiratory damage. For 15 years, Donald P. Tashkin and
colleagues at the University of California-Los Angeles have
probed the respiratory systems of hundreds of long-term, heavy
marijuana smokers. Their conclusion: Puff for puff, smoking
marijuana is even harder on the lungs than smoking tobacco.
"Smokers of marijuana had as frequent symptoms of chronic
bronchitis as smokers of tobacco, despite the fact that the
tobacco smokers smoked more than 20 cigarettes a day, compared
with the 3 to 5 joints a day used by the marijuana smokers,"
Marijuana smokers also had more microscopic damage to the lungs'
system of defense against inhaled contaminants and microbes, as
well as more precancerous cellular changes. An analysis of
marijuana smoke shows why this is so: It has 50% to 70% more
known carcinogens than tobacco smoke. And since marijuana joints
don't have filters and are usually smoked down to the last
fraction of an inch, they deliver more irritating particulates to
the lungs. Recreational users further magnify the damage by
inhaling the smoke deeply and holding it in as long as possible.
But does smoking marijuana actually cause cancer? It's too soon
to tell. "It's unusual to develop lung or upper airway cancer
under the age of 40, but after 50 it occurs with increasing
frequency," Tashkin points out. "The current marijuana epidemic
began in the late 1960s, and the bulk of the smokers are just now
reaching the age of 50. So we're just approaching the cusp of our
ability to show an association between marijuana smoking and
these cancers." It's also unknown whether the risk of cancer
would gradually decline after a person stopped smoking marijuana,
as it does with tobacco.
The Good It Can Do
Less is known about marijuana's beneficial side. For the past
decade, the government has refused to provide either money or
marijuana to researchers studying the drug's potential
therapeutic effects, so this research has been nearly at a
standstill. Early this year, however, in response to the Arizona
and California initiatives, the National Institutes of Health
called together an expert panel to consider possible areas of
research. The panel concluded that there's enough evidence of
smoked marijuana's usefulness to justify resuming studies.
Researchers are interested in three major areas where smoked
marijuana seems to work therapeutically:
Nausea from chemotherapy. Because it's illegal, there are no
figures available on how many cancer patients self-treat their
nausea with smoked marijuana. But a 1991 survey of more than a
thousand cancer specialists found that 44% had recommended it to
at least one patient, and that 48% would prescribe it if it were
legal. Before the federal government cracked down on research,
enough had been learned to persuade the U.S. Food and Drug
Administration (FDA) to approve, in 1986, the marketing of
dronabinol (Marinol). This drug, in pill form, contains THC to
treat nausea caused by cancer chemotherapy.
With a legal synthetic marijuana pill already available, why are
people still pushing for the right to smoke marijuana for medical
purposes? Because patients and doctors assert that the two do not
behave the same in the body. And a convincing body of research,
some of it now nearly two decades old, shows that smoked
marijuana suppresses nausea better than Marinol pills, and with
fewer side effects. Physicians speculate that one reason for the
difference is that smoked marijuana enters the bloodstream almost
instantaneously, allowing patients to control their dose, whereas
the oral version is absorbed slowly for some time. In addition,
there's the possibility that the complex mix of compounds in
whole, smoked marijuana somehow counteracts the more unpleasant
effects of pure THC, such as extreme dizziness and unsteady gait.
Some people maintain that newer antinausea medications have made
both Marinol and marijuana unnecessary. "The American Medical
Association and so forth, they're not clamoring for medical
marijuana, and I think for good reasons," says Billy R. Martin,
professor of pharmacology at the Medical College of Virginia and
a longtime researcher on the metabolism of marijuana. "There are
better drugs out there." One often cited as such is the
antinausea drug ondansetron (Zofran). But even the newest drugs
do not work for everyone, a fact that has led some patients to
continue using marijuana.
AIDS wasting syndrome. Marinol has, in limited clinical trials,
proved an effective treatment for wasting syndrome, the deadly
loss of appetite and consequent extreme weight loss that afflicts
many AIDS victims in the end stages of the disease. In fact,
Marinol is one of only three FDA-approved treatments for this
condition (the others are human growth hormone and a hormone
called Megace, or megestrol acetate). But some AIDS patients say
it's not an adequate substitute for marijuana. "All it did was
make me very groggy without enhancing my appetite," one said.
AIDS activists and the doctors who treat the disease report that
marijuana is also useful for suppressing the nausea that's a side
effect of several effective anti-AIDS drugs. Advocates of
providing AIDS patients with marijuana acknowledge the risks of
the drug to lung and brain, but point out that these long-term
effects matter little to someone with a terminal illness.
However, there's no firm evidence that marijuana is effective
against the wasting syndrome. That has never been tested in
clinical trials. Donald I. Abrams, an AIDS specialist at the
University of California-San Francisco, has been trying since
1993 to secure government permission to compare smoked marijuana
to Marinol pills. Abrams also hopes to assess marijuana's effect
on the immune system. Many years of research have produced
conflicting results, with some studies showing that marijuana
depresses certain components of the immune system and others
showing either no suppression or, occasionally, stimulation.
However, a long-term study of 1,500 HIV-positive men who used
marijuana found the drug use didn't seem to accelerate the
deterioration of their immune systems.
Spasticity. People with spinal cord injuries and multiple
sclerosis are prone to painful muscle spasms and tremors.
Existing drugs give only partial relief, with severe side
effects. There are many anecdotal reports that smoked marijuana
relieves those symptoms but, to date, no large-scale, controlled
clinical trial has compared marijuana with existing legal drugs.
"With smoked marijuana, patients get immediate relief, whereas
with the oral drug they get a delayed, big rush of
unpleasantness. When they take a smaller dose, it doesn't work,"
says Paul Consroe, a University of Arizona pharmacology
professor, who is studying the effect of marijuana on muscle
Researchers seem to have lost interest in one once-promising use
of marijuana: to treat glaucoma. They discovered early on that
marijuana reduced the intraocular pressure resulting from this
potentially blinding disease. However, the treatment never caught
on with more than a handful of patients. To keep pressure down,
marijuana must be taken every two to four hours, and patients
didn't like being high continuously. Also, many new drugs work
well, with minimal side effects.
Consumer Reports Recommendations
The evidence is convincing that long-term regular use of
marijuana exposes users to significant risk of lung damage. Many
may also suffer subtle but measurable cognitive and motor
impairments that persist for weeks after use stops. And, of
course, nonmedical use of marijuana is illegal everywhere.
However, compared with other drugs of abuse such as tobacco,
alcohol and cocaine, marijuana is much less addictive, if at all,
and there's no danger of death from an overdose.
A number of attempts have failed to isolate compounds from
marijuana that would achieve the desired therapeutic effects
without making patients high. "It seems that the same
neurological receptor controls all the effects, the good and the
bad," says Consroe.
Since an unknown but probably substantial number of people are
smoking marijuana with the expectation that it will help make
their AIDS or terminal cancer more tolerable, Consumer Reports
urges the federal government to permit further research in this
area, in order to better determine the drug's efficacy and side
In the meantime, Consumer Reports believes that, for patients
with advanced AIDS and terminal cancer, the apparent benefits
some derive from smoking marijuana outweigh any substantiated or
even suspected risks. In the same spirit the FDA uses to hasten
the approval of cancer drugs, federal laws should be relaxed in
favor of states' rights to allow physicians to administer
marijuana to their patients on a caring and compassionate basis.
Copyright Consumers Union of U.S., Inc., May 1997
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