A recent study has proved that smart people do more drugs, and explained why. The Jest of the article is: every type of people do drugs. Smart people do more drugs because they have the capability to do more drugs. Now how they determined the higher intelligence individuals from the lower was based on IQ, not always the most reliable source, but better than nothing.
They found that smarter people, that is, people with higher IQs are more prone to do stupid things, BUT, they realize that they are doing these things and seek to counterbalance this. For instance, if a person with a high IQ eats an entire pie, they are proven more likely to go to the gym after to work of the fat they had just gained than those with lower IQs. so, inherently when smart people do drugs, they do things that will repair their bodies as opposed to less intelligent people who will do the drug and not do anything beneficial for their body.
Story Here: http://www.psychologytoday.com/blog/the-scientific-fundamentalist/201010/why-intelligent-people-use-more-drugs