DOPE ON DOPE

You're absolutely right.

Even if every myth about cannabis causing "reefer madness" were true,
the harm caused by the drug would not justify sending users to prison
(3 November, p 3 and p 12). The zero tolerance approach both
victimises users and harms society at large. Prisons transmit violent
habits and values rather than reduce them. Most non-violent drug
offenders are eventually released with dismal job prospects due to
their criminal records.

Turning cannabis smokers into hardened criminals is a senseless waste
of tax dollars. Hopefully the common sense coming out of Britain will
rub off on the US. More Americans were arrested for cannabis in 2000
than all violent crimes combined.

For a drug that has never been shown to cause an overdose death, the
amount of resources used to enforce cannabis prohibition is
outrageous. The effectiveness of zero tolerance is dubious at
best--despite harsh penalties, the US has higher rates of cannabis use
than any European country. Sooner or later Britain is going to have to
take the next logical step. Decriminalisation acknowledges the social
reality of cannabis use and frees users from the stigma of criminal
records.

What's really needed is a regulated market with enforceable age
controls.

Separating the hard and soft drugs markets is critical. As long as
cannabis distribution remains in the hands of organised crime,
consumers will continue to come into contact with hard drugs.

Robert Sharpe, The Lindesmith Center Drug Policy Foundation, Washington, DC

David Fergusson was quoted as saying that he "can't explain away" the
correlation between marijuana use and subsequent hard drugs use found
in his study in New Zealand. But the hardly radical Institute of
Medicine, part of the US National Academy of Sciences, discredited the
"gateway theory" that marijuana leads to hard drugs use in its recent
report to Congress on the potential dangers of medical marijuana. The
report said, "There is no conclusive evidence that the drug effects of
marijuana are causally linked to the subsequent abuse of other illicit
drugs." Even Fergusson's paper qualifies his comments more than your
reporter suggests.

His abstract ends with the statement: "Findings support the view that
cannabis may act as a gateway drug that encourages other forms of
illicit drug use. None the less, the possibility remains that the
association is non-causal and reflects factors that were not
adequately controlled in the analysis." Let me suggest just one major
confounding factor.

Perhaps some people simply like taking drugs, and some of those people
like to take them more often than others and like to try many
different ones. This could explain why two-thirds of cannabis smokers
don't use other drugs--and why heavier smokers are more prone to use
other drugs--better than any pharmacological idea about pot changing
the brain.

Occam's razor needs to be applied with particular sharpness to
research on illicit drugs, which tends to serve political agendas far
more than scientific ones.

Maia Szalavitz, New York

You report that: "Although two-thirds of cannabis users [in the New
Zealand study] did not progress to other illicit drugs, nearly all
hard-drug users started off on cannabis." Could it not be that most
teenagers--and also most adults--use some sort of mild drug, such as
cannabis, nicotine and alcohol, and that a smaller subset of people
progress to harder drugs? The causal relationship for cannabis may
appear a little stronger because its illegality (and reputation)
probably keeps some potential users away, but I suspect most hard drug
users also began smoking cigarettes and drinking alcohol.

Don Churms, Charlottesville, Virginia

I was sorry to see you fall for an old statistical (or philosophical)
chestnut. "The link is undeniable," you say of the New Zealand study
that showed 99 per cent of hard drug users started with cannabis. An
unpublished study of my own reveals that 100 per cent of all drug
users and alcoholics started on milk, and by the same logic it is
clearly high time some action was taken to restrict access to this
dangerous white liquid.

Galen Ives, Sheffield

My experience as a clinician, for what it's worth, is that most
cannabis users who come to our attention--a minority of users who
experience trouble with the drug--have many other problems. This is
consistent with the literature. As recently as last week, at the
Australian Professional Society on Alcohol and other Drugs Conference
in Sydney, we heard of the high rate of association between
problematic cannabis use or "dependence" (I'm never sure what that is)
and other problems, but no evidence of a causal link. There was a call
for more treatment for cannabis misuse, but no evidence to suggest
that this would work any better than treatments of distress from
violence, abuse, mental health issues or chronic hopelessness. Given
that we have successful and cost-effective treatments for anxiety and
depression, and given that the benefits of early intervention have
been proven, this seems an unfortunate oversight. When users' other
problems are addressed, often by quite brief interventions, cannabis
use rarely continues to be an issue.

This, again, is consistent with results from studies of both
laboratory animals and humans.

But it seems easier to keep bagging cannabis, revealing the triumph of
dogma over evidence.

Susan Greenfield, the Oxford pharmacologist who opposes the
legalisation of cannabis, seems to have fallen into this trap.
Prohibition increases both the cost of this substance and the anxiety
associated with obtaining and using it, which often makes these
people's problems worse.

But it does not seem to prevent or reduce use. What should an
intelligent, evidence-based policy look like--surely not more of the
same?

Rod MacQueen, Orange, New South Wales

I would like to refer you to a study done on the gateway effect in the
Netherlands. "Keeping off, stepping on and stepping off: the
steppingstone theory reevaluated in the context of the Dutch cannabis
experience" by Stephen Sifaneck and Charles Kaplan (Contemporary Drug
Problems, vol 22, Autumn 1995). They found that the so-called gateway
effect is more likely due to criminalisation because of interaction
with dealers who often sell harder drugs as well, and that, as your
reporter Claire Ainsworth stated, separating markets does appear to
weaken the gateway effect. This study also found that alcohol abuse
was more likely to precede hard drug use than marijuana.

For example, alcohol abuse preceded 94 per cent of heroin use in the
study population, in contrast to 30 per cent having used marijuana.

So can we really say cannabis is THE gateway drug?

Dan Grubbs, Address supplied