Gateway drugs are drugs that serve as almost essential social and psychological precursors to use of other drugs, such as marijuana, heroin and cocaine, although the link between the gateway drug and the other drug is not biochemical. Cigarettes are the ultimate gateway drug. In 1987, a research team at the University of Michigan's Institute for Social Research found that among high-school seniors, daily cigarette smokers were 10 times more likely to use cocaine regularly than were seniors who never had smoked regularly. Students who never smoked were much less likely to experiment with controlled substances and very unlikely to use them regularly. A tobacco-free lifestyle serves as a powerful protective factor against abuse of controlled substances.
Studies show that the younger a smoker becomes addicted, the tougher it is to quit.