Cannabis: the slippery slope

Is cannabis use in young people the gateway to hard drugs? Yes, says Ann Stoker of the National Drug Prevention Alliance.

"One could draw a graph showing the increased use of cannabis, which will exactly mirror the escalation in the use of cocaine by young people,"she wrote in a letter to The Times on Monday 8 March. She was commenting on a Times article of 3 March, "Celebrity users made cocaine all the rage, say MPs" which cited British Crime Survey statistics. But was she right?

In terms of long term trends at least, the answer is no. Home Office Statistical Bulletin 12/09 Drug Misuse Declared: Findings from the 2008/9 British Crime Survey, shows that despite a recent small increase in young people's reported cannabis use, the trend since 2001 has been down. See graph, below.


 As The Times reported, however, cocaine use among young people has risen since 1996, as the statistical bulletin reported. See graph 2, below:


Ms Stoker also cited a now 35 year-old study by Kandel et al, Stages in adolescent involvement in drug use. This did indeed report that marijuana was "...a crucial step on the way to other illicit drugs".

But it also found that that legal drugs, specifically alcohol and cigarettes, were "necessary intermediates", and that "whereas 27 per cent of high school students who smoke and drink progress to marihuana within a 5- to 6-month follow-up period, only 2 per cent of those who have not used any legal substance do so".
If the latest BCS data undermines the 'gateway hypothesis', experts remain divided on other grounds.
"The role of cannabis in the gateway pattern of drug use remains controversial because of the difficulty of excluding the hypothesis that the gateway pattern is due to the common characteristics of those who use cannabis and other drugs" write Wayne Hall, Louisa Degenhardt and George Patton in Adolescent addiction: epidemiology, assessment and treatment [Chapter 4 Cannabis abuse and dependence, p127, editor Cecilia A. Essau, Academic Press, 2008].