Pubdate: Sat, 28 Oct 2000 Source: Times, The (UK) Copyright: 2000 Times Newspapers Ltd Contact: PO Box 496, London E1 9XN, United Kingdom Fax: +44-(0)171-782 5046 Website: http://www.the-times.co.uk/ Author: John A. Henry 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. - --- MAP posted-by: Richard Lake