http://www.scienceblog.com/cms/study-say-m...drug-12116.html

`Marijuana is not a “gateway” drug that predicts or eventually leads to substance abuse, suggests a 12-year University of Pittsburgh study. Moreover, the study’s findings call into question the long-held belief that has shaped prevention efforts and governmental policy for six decades and caused many a parent to panic upon discovering a bag of pot in their child’s bedroom.

The Pitt researchers tracked 214 boys beginning at ages 10-12, all of whom eventually used either legal or illegal drugs. When the boys reached age 22, they were categorized into three groups: those who used only alcohol or tobacco, those who started with alcohol and tobacco and then used marijuana (gateway sequence) and those who used marijuana prior to alcohol or tobacco (reverse sequence).

Nearly a quarter of the study population who used both legal and illegal drugs at some point – 28 boys – exhibited the reverse pattern of using marijuana prior to alcohol or tobacco, and those individuals were no more likely to develop a substance use disorder than those who followed the traditional succession of alcohol and tobacco before illegal drugs, according to the study, which appears in this month’s issue of the American Journal of Psychiatry.’