THE CASE AGAINST CANNABIS

In 1839, W. B. O'Shaughnessy, a professor of medicine at the University of
Calcutta, introduced cannabis into Western medicine. For the past 160
years, until recently, it has been doctors rather than schoolmasters who
have had the greater professional interest in the drug. Mixtures derived
from cannabis were regularly prescribed until the 1930s and 1940s for a
variety of ills. Queen Victoria and her doctor were firm advocates of a
cannabis tincture to treat her period pains.

This week Estelle Morris, the School Standards Minister, took the
discussion away from a world of white coats to one of mortar boards. In
fact, her remarks were not too revolutionary. She was not advocating any
laxity in the approach to the misuse of cannabis, merely more flexibility
in the punishment system.

Increased acceptance of the medicinal benefits of cannabis, taken in the
form of cannabinoid extracts, has tended to obscure the adverse reactions
of cannabis smoking. A few years ago, voguish doctors were apt to overrule
parental and even educational anxieties and encouraged the cannabis-smoking
young person to continue. They explained that they could see little
difference between the parent having a gin and tonic or half a bottle of
wine with dinner and the teenager puffing a joint.

Professor Wayne Hall, in association with Dr Nadia Solowij from the
University of New South Wales, has recently reviewed the less desirable
effects of cannabis in The Lancet.

Most cannabis users stop in their mid to late twenties; few smoke it for
more than a few years. In the US and Australia only 10 per cent become
daily users of cannabis, although 20 to 30 per cent use the drug weekly.
Daily cannabis smokers are more likely to be men, and tend to be less well
educated. They also take tobacco and alcohol regularly as well as a wide
variety of other drugs.

Cannabis may induce anxiety and panic in those unused to it. It reduces
concentration, impairs memory and muscular co-ordination in the long and
short term. This is the price that has to be paid for the euphoria and the
intensification of ordinary sensory experiences. The effects on memory and
concentration of persistent cannabis use are very subtle. It is not known
whether they are reversible after prolonged abstinence but, say the
authors, they do create a cannabis-dependent syndrome so that regular users
find it extremely difficult to give it up. The acute ill-effects include a
liability to accidents, particularly when, as is often the case, the
cannabis is combined with other drugs or alcohol.

The capacity of cannabis to increase the risk of psychotic symptoms should,
in many doctors' opinion, be enough to discourage its use. It is unlikely
that cannabis smoking may "cause" an acute psychotic breakdown but the
overwhelming evidence is that it can induce this in those who, because of
their lifestyle or their heredity, will be prone to schizophrenia and its
related conditions. The temperament and interests of those who may be in
danger of developing mental illness may also draw them to cannabis smoking
circles. The continued use of cannabis may not be as obviously mentally
destructive as that caused by long-term excessive drinking but the longer
the patient has been smoking pot, the greater the impairment. This damage
not only affects the person's overall intellectual ability but the subtler
aspects of reasoning and decision-making.

Cannabis smokers should realise the physical diseases induced by smoking.
They develop chronic bronchitis, just as tobacco smokers do, and their
lungs show the changes that are precursors of malignant disease. There may
be an increased risk of cancers of the mouth, pharynx and gullet, and there
is evidence that leukaemia is more common among babies born to mothers who
smoke cannabis when pregnant.

Professor Hall and Dr Solowij are adamant that those who should avoid
cannabis are disturbed adolescents with poor school performance, people
with a family history of schizophrenia and its related diseases, patients
with asthma, bronchitis, emphysema, those who have already shown a tendency
to over-indulge in alcohol or other drugs and, of course, pregnant women.