(CBS) -- 25-year-old Stephanie Cardamone knows how crippling anxiety and depression can be.
"Looking back on my entire life, it's just like situations that I'm thinking of where I'm like that wasn't normal," she says.
She was diagnosed with depression in her early 20's, but she recalls symptoms much earlier.
"It was there, in my teenage years, I just didn't know what it was, I didn't know how to deal with it."
Now the American Academy of Pediatrics is issuing updated guidelines on adolescent depression. Research shows by age 20, about 20% of teens say they've experienced some depression, which can affect them long term.
"It can lead to social problems, family problems. School problems...Substance abuse," says Dr. Rachel Zuckerbrot with Columbia University's Irving Medical Center.
The goal is to help pediatricians identify depression early.
The new guidelines recommend doctors talk about mental health with adolescents and their parents and implement universal depression screening for children 12 and older.
Dr. Zuckerbrot says it's important to also keep a close eye on at-risk children.
"Those include children who have a family history of depression and other mental health issues, children who have already had an episode of depression," she says.
Stephanie works with the Anxiety and Depression Association of America to raise awareness.
"I just think it's really important, no matter what someone's going through, to make sure they don't feel isolated," she says.
… So others spot the signs and seek help.