It's the 40th anniversary of the gateway drug theory. What led you to propose it?
There had been a large increase in the use of marijuana in the 1970s. I was funded to do a project focused solely on marijuana, but I thought that it might also be interesting to look at other drugs, so I slipped some questions about drinking and smoking into the interviews.
Once I started looking at the data, I realised that there were certain ages at which people tended to get involved in different classes of drugs. They tended to start on cigarettes, alcohol and marijuana at around ages 12 to 14. By doing cross-sectional and longitudinal studies of drug use, I found the same pattern over and over again.
What was that pattern?
People started with legal drugs such as wine, beer and cigarettes, and some progressed to marijuana. Then some moved on to cocaine, and ...
To continue reading this article, subscribe to receive access to all of newscientist.com, including 20 years of archive content.
