DANGEROUS HABITS

3 years ago, a Lancet editorial began, "The smoking of cannabis, even long
term, is not harmful to health" (Nov 11, 1995); an assertion criticised by
many readers as encouraging an indulgence that is illegal in many
countries. Predictably, the legalise-cannabis lobby seized on The Lancet's
apparent endorsement of this substance's safety. This week we publish a
seminar on the adverse effects of cannabis (p 1611) . Wayne Hall and Nadia
Solowij conclude that the most likely adverse effects of smoking cannabis
are bronchial irritation, the risk of accidents when intoxicated,
dependence, and possible cognitive impairment with heavy, long-term use.

The evidence summarised in this seminar was considered by a committee of
the UK House of Lords which reported on Nov 11 . The committee recommended
that clinical trials be done on the effects of cannabis in multiple
sclerosis and in chronic pain, and that the UK Government should reclassify
cannabis so that it can be prescribed by doctors under certain circumstances.

The debate about whether or not cannabis, taken for recreational rather
than medical reasons, should be legalised in countries where it is banned
will rumble on, and further complicate scientific assessment of the
therapeutic effects of cannabinoids. The arguments advanced by each side
are well-rehearsed, but usually fail to consider the problems presented by
cannabis in a wider perspective. We would, perhaps, have been wiser to have
begun our editorial 3 years ago with a less provocative statement; but, on
the evidence summarised by Hall and Solowij, it would be reasonable to
judge cannabis less of a threat to health than alcohol or tobacco, products
that it many countries are not only tolerated and advertised but are also a
useful source of tax revenue. The desire to take mood-altering substances
is an enduring feature of human societies worldwide and even the most
draconian legislation has failed to extinguish this desire--for every
substance banned another will be discovered, and all are likely to have
some ill-effect on health. This should be borne in mind by social
legislators who, disapproving of other people's indulgences, seek to make
them illegal. Such legislation does not get rid of the problem; it merely
shifts it elsewhere.

One aspect of taking mood-altering substances may require legislation: the
protection of others from annoyance and harm. Whether or not a person's
indulgence poses a threat to others has been used as a guide to define the
limits of socially acceptable behaviour; although to do so begs the
question of people's responsibility for themselves. Should it be, for
example, permissible for people deliberately to put their lives or health
at risk through participating in dangerous sports such as boxing or motor
racing? Do people have the right to decide for themselves what risks to
take, irrespective of any expense and inconvenience to others when the
risks come home? Is it reasonable to say "It is my life, I shall do as I
choose", when almost everyone shares their lives with friends or family who
would be damaged by their illness or death? Whatever the answers to these
questions, there is one aspect that is indisputable: people have the right
to know what are the risks to themselves and to others.

2 weeks ago, we published evidence that the sustained use of
3,4-methylenedioxymethamphetamine ("Ecstasy") was associated with a
decrease in serotonin neurons in the brain (Oct 31, p 1433) . This is
information that any user of Ecstasy has a right to know; just as users of
cannabis should be aware of its possible hazards. Because the debate about
use of cannabis arouses strong emotions, there is, as Hall and Solowij
note, no "consensus on what health information the medical profession
should give to patients who are users or potential users of cannabis."
Doctors called upon for advice about use of cannabis will find the authors'
last paragraph a useful source of dispassionate information. The advice is
little different from that appropriate for many other mood-altering
substances: do not drive motor vehicles whilst intoxicated and do not
overindulge.

We will qualify our opinion of 3 years ago and say that, on the medical
evidence available, moderate indulgence in cannabis has little ill-effect
on health, and that decisions to ban or to legalise cannabis should be
based on other considerations.


Checked-by: Pat Dolan