Researchers of the University of Pittsburgh found that nearly a quarter of the young men in their study used cannabis before they began drinking alcohol or smoking cigarettes. It's the reverse of what's known as the "gateway hypothesis," in which drug use is thought to progress from alcohol and tobacco to cannabis to hard drugs. The researchers determined also that the likelihood of developing a substance abuse problem was similar in youngsters who followed the traditional gateway drug use pattern and those who followed the reverse pattern. More at: http://ajp.psychiatryonline.org/cgi/content/abstract/163/12/2134 (Source: Tarter RE, et al. Am J Psychiatry 2006;163(12):2134- 2140.)