Submitted by Mary Brett, Dr Challoner's
1.1 As a biology teacher and head of health
education of 27 years in a large State Grammar School for Boys,
I have watched with mounting alarm the growing clamour for the
decriminalisation of cannabis. My main concern is how cannabis
affects the brain, particularly the processes of learning and
memory and the personality of the user. I have witnessed these
detrimental effects in some of my pupils.
1.2 Decriminalisation would inevitably increase
useit always does! Even if use were restricted to the over
18s, (cannabis like alcohol is an intoxicant), school children
would still be targeted, and access would be made easier for them
through older siblings. Surely under-age drinking has taught us
2. How Drugs Work in the Brain
2.1 Messages pass along the nerve fibres
as electrical impulses and cross the gaps between nerve cells
as chemicals (neurotransmitters). These are the brains natural
"drugs", each having a particular shape to fit the receptor
site on the membrane of the next cell, rather like a key fitting
a lock. Unfortunately, the brain cannot distinguish between these
neurotransmitters and the "mind altering" drugs that
people take. Cannabis mimics the neurotransmitter anandamide (ananda:
Sanskrit for "bliss") to give the "high".
It also occupies the same receptors sites as the opiatespossibly
explaining its pain control properties. The psychoactive ingredient
THC (tetrahydrocannabinol) dissolves in the far rich cell membranes
and remains there. 50 per cent will still be there a week later
and ten per cent after a month. Traces in the hair and urine will
be detectable for weeks.
2.2 Since THC is blocking the membranes,
the orderly release of the many other neurotransmitters is disrupted.
Not only does this impair the everyday functioning of the brain,
but also the new connections, vital for the processes of learning
and memory are not made. This is especially serious in adolescence,
normally a time when a "growth spurt" of these connections
occurs. Incidentally a joint today contains on average ten times
as much THC as it did in the Sixties.
3. The Immediate Effects
3.1 It takes about 20 minutes for the effects
of a smoked joint to peak, they last for two to three hours. Even
with low doses, there is a huge downside to any feelings of euphoria.
Thought processes fragment, there is an inability to sustain concentration,
learning ability decreases and short-term memory deteriorates.
This refutes the claim that cannabis actually helps study. Handwriting
and motor co-ordination are consistently impaired.
4. Long-Term Effects
4.1 Since the late Eighties, Swedish and
Australian researchers have used new and more sensitive techniques
to investigate these. They found that sustained use of cannabis
impairs the ability to carry out tasks requiring complex thinking,
intellectual flexibility, forward planning and processing of information.
There is consistent interference with short-term memory, an inability
to cope with new situations or benefit from past experiences.
4.2 Dr Nadia Solowij, an Australian researcher
said in her book "Cannabis and Cognitive Function" (1998)
"Use more often than twice per week for even a short period
of time, or use for five years or more at the level of even once
per month, may each lead to a compromised ability to function
to their full mental capacity, and could possibly result in lasting
4.3 No child using cannabis, even occasionally,
will achieve his or her full potentialI know, I have seen
it happen. It does not help that most of the messages youngsters
receive, even from drug educators, dismiss cannabis as being "no
big deal". We would raise educational standards at a stroke
if we could only persuade our children to abstain.
4.4 A former pupil who had been in trouble
with cannabis at school said, "Tell them that they will become
boring people. They won't want to go out, they'll sit watching
TV and have no conversation". Most of his friends didn't
make it to university. He scraped in. When he gradually realised
that everything I had said about cannabis was true, he stopped,
and is now doing research towards a PhD.
4.5 Dr Solowij was not alone in hinting
that damage to the brain may be permanent. In 1997 the WHO Report
on Cannabis stated in its summary "The chronic use of cannabis
produces additional health hazards . . . which may not recover
with cessation of use, and which could affect daily life functions".
4.6 Attempts to answer this question by
experiments and brain scans have been inconclusive. But there
are many things we accept without conclusive proof, such as the
connection between smoking and lung cancer. Surely we should err
on the right side of caution.
4.7 Many clinical and anecdotal reports
of long term impairment of mental functions exist especially from
the developing countries. Permanent brain damage is a distinct
possibility for cannabis users. It would be slow, subtle, insidious
but cumulative. The risk is too great. Dead brain cells are never
replaced and since they work in chains, if one cell dies, the
whole message is lost.
5. Personality Changes
5.1 Cannabis users assume a different identity.
They become passive, inflexible and rigid in thought. Since they
never question their actions they're unable to change. They cannot
take criticism and feel misunderstood. The negative feelings induced
by the drug encourage more consumption and so the downward spiral
continues. Trying to talk sense to users becomes a futile exercise.
5.2 Youngsters have to forge an identity
for themselves. They must eventually be able to fit into the adult
world. New relationships have to be made and the world viewed
in a realistic way. Cannabis use consigns them to a childish level
of development, lacking independence and ill-equipped to make
5.3 A long-running study of cannabis using
children in 1988 found a higher level of psychosis and an undesirable
social network in early adulthood. They were more likely to drop
out of education, find it harder to hold down a job and were more
likely to divorce.
6. With decriminalisation would come increased
usage. More children would progress to hard drugsthey did
in Holland. It does not bear thinking about.