Learning to overcome fear is difficult for teens, brain study finds

"A new study by Weill Cornell Medical College researchers shows that adolescents' reactions to threat remain high even when the danger is no longer present. According to researchers, once a teenager's brain is triggered by a threat, the ability to suppress an emotional response to the threat is diminished which may explain the peak in anxiety and stress-related disorders during this developmental period."

http://medicalxpress.com/news/2012-09-difficult-teens.html