Now, a government task force is asking doctors to check all teenagers for depression regularly.
Behind the statistics are teens like 18-year-old Taryn. She felt so depressed, anxious and isolated in 9th grade, she started using hard drugs and ended up in rehab at Visions Adolescent Treatment Centers.
"It was just getting so out of control that I couldn't wake up and have a normal day anymore," Taryn says.
Most major teen depression goes undiagnosed and untreated, Whitaker reports.
Dr. Ned Calonge, Chairman of the Preventive Services Task Force says all adolescents age 12 to 18 should be screened for major depressive disorder.
The influential task force recommends that pediatricians screen all teens annually - not just those with obvious symptoms - with detailed but simple questions on mood, anxiety and substance abuse, like, how often have you been bothered by:
The screening is designed to identify "Not just a bad day or disappointment but something that's present in the child's life for weeks or even months," says Dr. James McCracken, a professor in child psychotherapy at UCLA.
"This isn't a recommendation to test for depression and then treat with drugs alone," says Dr. Calonge.
But doctors are convinced widespread screening and treatment, especially talk therapy, can improve and save young lives.
By Bill Whitaker