http://www.scientificamerican.com/podcast/episode/high-iq-kids-later-try-drugs-more-11-11-22/
Having a high IQ may have its drawbacks: a new study finds that highly intelligent children are more likely to try illegal drugs in their teenage and adult years. The work is published in the Journal of Epidemiology and Community Health. [James White and G. David Batty, "Intelligence across childhood in relation to illegal drug use in adulthood: 1970 British Cohort Study"]
An ongoing study that started in 1970 gathered data from 8,000 people, including their IQ test scores at ages five and 10. Participants later reported their history of illicit drug use at age 16, and then again at age 30.
Men with high childhood IQs were 50 percent more likely to use drugs than their low-scoring counterparts. And women with high scores were more than twice as likely to have tried controlled substances.
I don't think experimentation is necessarily bad - most everyone who does so stops a lot of "risk-taking" behavior when they take on adult responsibilities. They just need to be informed about possible drawbacks (not false "gateway" propaganda.)
But, again, you have smart kids who happen to be in poverty situations that afford them little opportunity - so, like Kurt Schmoke said long ago - these are entrepreneurs in a market that allows them entry, while they are shut off from other opportunities - this is the real gateway - lack of opportunity.
Legalize and put the tax revenue toward education, especially among "at risk" populations due to poverty or lack of social support, etc.