CALCULATING THE RISKS OF MARIJUANA USE

Talking about the physiological effects of marijuana can be a little like
talking about religion -- perspective counts.

Marijuana causes seizures; marijuana can treat seizures. Marijuana causes
panic attacks; marijuana relieves anxiety. Marijuana may precipitate
schizophrenia and causes depression; marijuana improves mood.

What is going on here? The problem is that an individual's acceptance of
one side of these statements over the other is more dependent on belief and
perspective than on scientific evidence, of which there is a little, for
all of these statements.

It has been difficult to get really good studies on the effects of
marijuana for a number of reasons, including the regulatory barriers
arising from its legal status. In addition, the content of THC (the main
active ingredient) varies widely, an individual subject's history of
marijuana use affects his/her response, and many potential subjects who
have had a bad experience with marijuana choose not to volunteer to be studied.

The other reason that perspective matters so much is that if one is
interested in the medicinal aspects of marijuana, then everything else
becomes "side effects," and, depending on the seriousness of the condition,
one may be willing to tolerate significant side effects. However, if one is
primarily interested in the psychoactive effects of the drug, then other
hazards such as damage to organs, addiction potential, withdrawal symptoms,
and impairment of other functions are more important considerations.

In fact, there are some things that we really do know about the
physiological effects of marijuana. The plant contains potent psychoactive
chemicals called cannabinoids, of which THC is the most abundant.
Interestingly, there are cannabinoid receptors in the human brain, as well
as chemicals produced by the body that bind to the receptors and cause
changes in the nerve cells. We do not yet fully understand the effects of
these internally produced chemicals.

We know that the acute psychoactive effects of the cannabinoids include
euphoria, talkativeness, and dreaminess, followed by lethargy, and
sleepiness, though some individuals experience panic attacks, depression
and even hallucinations. Blood flow in the brain has been measured to
decrease in some areas and increase in others after use. There is
short-term memory loss and impaired performance of complex tasks, both
mental and physical.

Individuals who use marijuana are at risk of developing dependence on the
drug, particularly adolescents or those with psychiatric disorders. There
is a newly described, distinctive withdrawal syndrome, which is similar to
but milder than that due to alcohol and opiate withdrawal.

Especially worrisome is the damage caused to lung tissue by inhaled
marijuana smoke. British research has shown that the impact per puff is
many times worse than that of tobacco, because of the large amount of tar
deposited. Since many marijuana smokers also smoke tobacco, the cumulative
effect on lung tissue can be very damaging. Chronic marijuana smokers
report the same amount of bronchial irritation and coughing as tobacco
smokers over the same time period, though the amount of marijuana smoked is
usually much less. In fact, smoking approximately one and a half joints is
equivalent to a half pack of cigarettes in terms of lung damage. Cellular
and molecular studies implicate marijuana as a carcinogen.

Also of concern is the fact that adolescents and young adults are at risk
of both experimenting with marijuana and of becoming dependent on it. Data
from students at college show the more that students smoke marijuana, the
higher their risk for lower grades and dropping out of school. They also
are at higher risk for alcohol and other drug abuse, unprotected sex, and
tobacco use. All of these can affect their academic goals as well as their
long-term health.

Too many students draw the incorrect inference that, "It doesn't kill you
like alcohol can, therefore it is safe," rather than weighing the known
physiologic and psychologic impacts on their lives, both current and future.

Although we are learning that there are potential legitimate medicinal uses
of cannabinoids, we also know that there are serious harmful effects for
recreational users. The acceptance of risk of these effects must be
considered in the context of its use.