THE ART AND SCIENCE OF EVIDENCE ABOUT DRUGS

It Is Very Difficult To Study The Relative Harms Of Individual Drugs - And
There Are Lots Of Vested Interests

The government claims to want to pursue "evidence-based policy". I've
often wondered whether there is any evidence that evidence-based
policy is better than its alternative. What alternative? Daily
Mail-based policy, of course.

The issue has been in the news lately because of the Nutt affair: the
sacking of the chair of the Advisory Council on the Misuse of Drugs,
who has been arguing that government policy on drug classification
runs foul of the scientific evidence.

I've been following the work of Professor David Nutt even before the
newspapers took interest, since sitting on a working party on drug
regulation for the Academy of Medical Sciences. As a newcomer, I
wanted to find the "facts on drug harm", and read Nutt's A tale of two
Es - ecstasy and ethanol (alcohol) - published in 2006. According to
the statistics in this paper, there is not a single dimension on which
ecstasy is known to be more harmful than alcohol. Nothing. Alcohol
causes death in large numbers, brain and liver damage, violence and
public disorder. Ecstasy helps white men dance and makes them hug each
other. Tragically, it also leads to some deaths, but then,
notoriously, so do horse riding and peanuts.

Nutt, of course, has his academic critics. One of them, Professor Andy
Parrott, wrote in a letter to the Evening Standard on 3 November: "All
recreational drugs cause more harm than benefits ... ecstasy [leads to]
depression, memory loss and impaired immunocompetence (more coughs and
colds)". I see, so that's why you can go to prison for possessing it. It
gives you sniffles, just like not drying your hair properly after your
swimming lesson.

A lot is known about the harms of alcohol. A lot is known about the
harms of drug overdoses and infections. But very little seems known
about the health effects of taking a regular, clean dose of many drugs.

It is a very hard area to study. Randomised controlled trials won't
pass the ethics committee. Observational studies are little help. Most
drug users use several different drugs, including alcohol, so harm
cannot be attributed to a particular source. Longitudinal research
would be helpful, but addicts, funnily enough, tend to drop out of the
research cohort. Drug researchers end up studying only those users
they can catch: the ones who turn up in clinics with a crisis.
Something of a skewed sample, of course.

Animal experiments are an alternative. There is some great work
looking at the types of webs spiders spin under the influence. More
relevantly, a paper from 2003 in the leading journal Science claimed
that primates injected with a recreational dose of ecstasy developed
brain damage. Very worrying. But a few months later, when they
couldn't replicate the experiment, the researchers published a
retraction, saying that the primates were given crystal meth by
mistake, which has a very similar chemical name and was delivered to
the lab on the same day. Whoops.

For many drugs there seems little evidence of physical harm. But that
shouldn't be confused with the very different claim that there is
evidence of little physical harm. So how can Nutt be so confident
about relative harms? Isn't there a famous bar chart, showing that
heroin and cocaine are the most harmful drugs, with alcohol and
tobacco more dangerous than cannabis, ecstasy and LSD? Well, yes there
is, and it was published in The Lancet. But because so little hard
evidence is available, the methodology was "Delphic": ask the oracle,
in this case a collection of drugs experts. In fact, the table made
its first appearance in an appendix to a Commons select committee
report, where the initiative to calculate drugs harms was welcomed,
but the committee noted that this particular attempt "is almost as
much an art as a science".

So we have the spectacle of scientists over-claiming the quality of
their results to publicise their research, journalists whipping up a
moral panic to sell newspapers, politicians doing whatever they think
will keep them in power, and the public looking on in semi-horror, as
one would on a reality TV show spinning out of control. So, to
paraphrase the great Jonathan Aitken, if it falls to me to start a
fight to cut out the cancer of bent and twisted science, politics and
journalism in our country with the simple sword of truth and the
trusty shield of British fair play ... forget it. Just pour me a glass
of wine, and turn on The X Factor, please.

Jonathan Wolff is professor of philosophy at University College
London. His column appears monthly