One in eight high school students is depressed. But depression in teenagers can be deceptive, and authorities estimate that a huge number of depressed teens are undiagnosed. Adults may mistake symptoms as "typical" teen angst, anger, or anxiety. Or the teen may mask the symptoms with high-energy activity.For parents who suspect their teen is depressed, the system often fails the family. Insurance coverage for treatment ends too soon, there's a months-long...