No significant changes detected in Colorado or among high school seniors in Washington; eighth- and 10th-graders in Washington are a different story.
One thing not discussed: self-reporting by adolescents is notoriously bad. Via Reason:
A new analysis of survey data finds that marijuana legalization was associated with more cannabis consumption among eighth- and 10th-graders in Washington but not among 12th-graders in that state or among Colorado students in any of those three grades. The study, published yesterday by JAMA Pediatrics, thus provides ammunition to both sides in the debate about how legalizing marijuana for adults affects adolescent use.