CANNABIS KILLS

As support grows for the decriminalisation of the so-called soft drug
marijuana, Dr Thomas Stuttaford explains why advocates of change need
to consider the long-term consequences - mental and physical - of
such a move

One of the social paradoxes of the 21st century is that the more
environmentally friendly and green a person's lifestyle, the more
likely he or she is to discuss the evils of pollution, carcinogens,
the dangers of DNA research and questions of genetic make-up -- while
enveloped in the blue haze of cannabis smoke.

The youthful protesters against global industry and the
pharmaceutical industry (which has revolutionised medicine and
agriculture, helping to prevent mass starvation in the developing
world), are also those who advocate the taking of a drug, cannabis,
that would fail its safety tests at the animal stage of testing, let
alone unrestricted use in human beings. This is why I do not support
its legislation.

Few doctors have not seen the sudden mental changes that can follow
intoxication with cannabis. In the short time that I was involved
with large numbers of drug-dependents -- mainly, but not exclusively,
young people -- it was a comparatively common occurrence. The
argument always deployed to belittle the importance of this
well-known phenomenon is that the personality of many of those who
are apt to become cannabis-dependent is essentially a flawed one, and
that the easygoing, hearty rugby or hockey player with an outlook as
phlegmatic as that of his or her parents would not be affected in the
same way.

Even if this were true, it ignores the obvious truth that there is a
large and important minority of people, often clever and aesthetic,
but with a vulnerable personality, who might have had happier and
more productive lives if they hadn't smoked pot and developed one of
the psychological conditions associated with it.

The ability of cannabis to change the slightly bizarre behaviour of a
young person carrying a genetic disposition to schizophrenia, from
that described as being characteristic of a schizotypal personality
disorder, to the disordered thought and behavioural pattern of
someone with a frank psychosis is now accepted. The ability of
cannabis to cause other psychotic and neurotic conditions, as well as
precipitating schizophrenia, is well documented. Likewise, its
deleterious effect on short-term memory, with all its attendant
disadvantages, is well known.

The physical disadvantages of cannabis are less well described. Young
people rarely think about mortality: death is for older age groups.
They may worry, or claim to worry, about the long-term effects of
pesticides, food additives, exhaust pollution and eating the right
sort of fat (in the more extreme cases, no fat at all), but they
prefer to ignore that even in the short term, cannabis can be a
killer.

Twenty years ago M.B. Holmberg presented statistics based on a study
of 1,000 16-year-olds that showed that those who had been regular
cannabis smokers at that time were five to eight times more likely to
have died over the following ten years. Not only were they more
likely to have ended up at the undertakers but there was a greater
probability that they had spent time in hospital or under the care of
doctors or social workers. They had a greater incidence of disease
and social problems.

In Holmberg's study 10 per cent of the regular cannabis smokers at
the age of 16 were recognised as suffering from a psychosis during
the ten-year follow-up period. Much of the excess mortality in young
cannabis-takers occurred among the psychotic patients who obviously
were prone to suicide and accidental death. A study has shown that
even in the early 1980s, when cannabis wasn't as strong as it is now,
someone who smoked cannabis once every ten days ran nearly
two-and-a-half times the risk of being involved in a road accident.

A later survey has put the risk of road accidents greater than this.
D.H. Gieringer, writing on marijuana, driving and accident safety in
The Journal of Psychoactive Drugs, suggests that the true figure of
accident-proneness in driving is three to five times that of those
who do not use cannabis regularly. This was demonstrated to me many
years ago when I was working with drug-dependent patients. I was to
speak in a debate opposing the legalisation of cannabis. My opponent,
a university lecturer of great charm, offered to give me a lift to
the debating hall because he wanted to demonstrate how
cannabis-smoking did not affect driving. After a terror-inducing
drive, which could compete in the nonchalance stakes with a French
taxi driver's, he abandoned the car -- parking would not be the right
word -- feet from the pavement.

He was happy with his performance. "There you are, Tom," he said, "I
told you it would be nothing like driving with someone who has been
drinking."

Not all the excess deaths of regular cannabis-takers, as opposed to
non-smokers, can be attributed to suicide and accidents. Cannabis has
been commonly smoked in Western society for only the past 40 years or
so. So its long-term effect as a cancer inducer has until recently
been conjectural. It is known that there is twice as much tar in
cannabis as in tobacco, and there is evidence that this tar is
carcinogenic. Tests have shown that most cannabis smokers --
President Clinton is the obvious exception -- aim to inhale deeply
and to retain the smoke for as long as possible.

As a result of these two factors, a person who smokes a joint rather
than a cigarette will ingest four times as much tar. It is not
therefore surprising that not only does the tissue of cannabis
smokers show pre-malignant changes but that there is now evidence of
an increased incidence of many cancers. Research workers at New
York's Memorial Sloan-Kettering Cancer Centre, one of the top ten
cancer centres in the world, found that on average regular smokers of
cannabis were 30 times more likely to develop cancer of the neck,
throat, mouth and larynx than those who never inhale marijuana. Other
research in the early 1990s demonstrated that these tumours appear
between ten and 30 years earlier than in non-cannabis takers. These
cancers struck more often and at an earlier age in cannabis smokers
than in other people.

The Sloan-Kettering researchers analysed their statistics. The
response, as would be expected, was dose-related. The risk of head
and neck cancer was doubled by smoking any marijuana, and those who
smoked more than a joint a day increased the incidence by five times.
If they also smoked cigarettes, as most did, the incidence of head
and neck cancers increased 36 times. Cigarettes and cannabis are a
deadly mixture. The SloanKettering researchers, like those from the
Swedish National Institute of Public Health, had no doubts about the
ability of cannabis to induce cancer of the lungs, mouth, pharynx
(throat) and larynx (voice box). In all probability, it also
increases cancer of the oesophagus.

Workers on psycho-active drugs have also studied the effects of
cannabis on the heart and cardiovascular system. They have shown that
when patients are stoned they suffer palpitations, cardiac
arrhythmias and a drop in blood pressure that may, for instance,
induce dizziness when they stand up.

In a fit young person the general view is that these changes are more
likely to be inconvenient and disturbing than dangerous. There have
been one or two cases of heart attacks recorded in young people after
heavy cannabis use, but they were not shown to be necessarily the
result of the heavy cannabis use.

The news is less encouraging for those who smoked cannabis in the
1960s and 1970s and have never given it up. They should not be too
sanguine about its effect on their ageing cardiovascular systems.
Older people with heart disease or high blood pressure have been
shown to be adversely affected by smoking cannabis. Whenever cannabis
and hormones are discussed, the story is usually told of a young
Swedish patient who had started smoking cannabis before he was 12. He
was a heavy cannabis smoker by the time he was 16. The boy was
undersized, had no pubic hair, small testicles and an underdeveloped
penis. His testosterone levels were abnormally low for a boy of his
age.

He stopped smoking and it was as if a miracle had happened. He grew,
his testosterone levels returned to normal and once again he could go
proudly into the communal showers after PE. This is only a single
case and has therefore little scientific value, but it is a good
illustration of an extreme example of the changes that can follow
heavy smoking of cannabis.

Men who smoke too much cannabis may well, for instance, develop heavy breasts.

When I was working in Whitechapel a Rastafarian told me that he could
notice no difference between alcohol and a spliff. "You drink whisky,
doctor, and become impotent; I take ganga and become impotent. The
only difference is that I get red eyes and you don't." He was right
about the whisky, and the red eyes, but knew nothing about my sex
life -- it was in pre-prostatectomy days. To judge from my chats with
heavy cannabis takers, it seems that though they claimed the drug
enhanced sexual sensations, in many cases it also reduced potency.

It is known that heavy doses of cannabis can induce foetal
malformations in animals. There has been much argument about whether
it also causes an increase in stillbirth and foetal abnormality rate
in human beings. At present, the case for this could be described
only as unproven, but it reduces sperm counts, and when there is so
much worry from the green movement about the reduction in sperm
counts over the past century, it would seem a pity to hasten the
process.

Most of us with children and grandchildren whose own opinions on the
legalisation of cannabis weren't formed by its widespread use in
undergraduate days will continue to worry about its psychological and
neurological effects (admirably described recently by Professor Susan
Greenfield in The Times). The former has been a source of anxiety for
40 years.

We should never forget that cannabis induces both physical and mental changes.