FRIDAY, April 25, 2014 (HealthDay News) -- American teens' use of marijuana doesn't increase when states approve the drug for medical use, a new study finds. "Any time a state considers legalizing medical marijuana, there are concerns from the public about an increase in drug use among teens," principal investigator Dr. Esther Choo, an attending physician in the department of emergency medicine at Rhode Island Hospital, said in a hospital news release. Choo's team examined 20 years of data from states that do and don't permit medical marijuana use. They found that legalizing medical marijuana did not lead to increased...