A VOICE FOR SCIENCE IN DRUG DEBATE

Sir, Much of the recent debate about cannabis (letters, October 21,
etc) has been too dismissive of its dangers. There is a confluence of
evidence that cannabis can cause dependence.

An Australian study found that about 15 per cent of regular cannabis
users developed dependence, while recent American research shows that
withdrawal results in physical as well as psychological distress, and
in craving.

There is also scientific evidence for cannabis-related harm of several
kinds. Work from the US and elsewhere suggests that cannabis use can
directly cause chronic bronchitis and lung cancer, in addition to the
secondary consequences of linked exposure to tobacco.

Cannabis probably causes impairment of so-called executive brain
function, as reported in a recent Australian research monograph.
Exposure of young people to cannabis is associated with decrements in
academic achievement.

South African research has confirmed that the drug can cause acute
psychotic disturbance severe enough to require emergency psychiatric
admission, and it can also cause relapse in otherwise successfully
treated schizophrenics.

Very properly it is society and not the scientists who will ultimately
decide what we do about cannabis. But with such serious, multiple,
large-scale and long-term public health consequences likely to flow
from any relaxation in control, it is perilous for the voice of
science to be drowned out by campaigners for legalisation who are
dismissive of the mounting evidence on dependence and harm.

Yours faithfully, JOHN A. HENRY, Academic Department of Accident and
Emergency Medicine, Imperial College School of Medicine, St Mary's
Hospital, W2 1NY.