Many studies show that early treatment using medication or talk therapy may prevent depressive episodes.
"Remember, depression isn't an attitude a teen is choosing," Besser said. "It's a serious and real brain disorder."
But for many teens, the symptoms of depression remain unrecognized. And unrecognized depression in some teens, including Maggie's brother, can lead to suicide.
Indeed, suicide is the third leading cause of death for people 14 to 24, according to the Centers for Disease Control and Prevention. And more than 600,000 teens make an attempt every year.
Maggie said she believes her brother would be alive today if someone, including himself, had recognized the warning signs.
"Every single day I have to wake up and I don't have my brother," Maggie said. "And maybe things could have been different."
For more information on teen depression and how to recognize the warning signs, visit: Families for Depression Awareness at http://www.familyaware.org , aevidum at http://www.aevidum.com/aevidum/Welcome.html and the Minding Your Mind Foundation at http://mindingyourmind.org/