(CNN) -- When we lose a beloved superstar like Robin Williams to an apparent suicide and learn he had been battling severe depression before his death, it's natural to think about our own loved ones.
We might look around at our adult family members and friends who are suffering and try to get them the help they need, but what we might not see is children and adolescents can get depressed and anxious, too.
And it's more common than we probably realize.
On any given day, according to studies, it is estimated that about 2% of elementary-school-age children and about 8% of adolescents suffer from a major depression, and 1 in 5 teens has had a history of depression at some time, according to the National Alliance on Mental Illness.
But how does a parent differentiate between what might be considered normal irritability and moodiness, especially during those teenage years, and signs that something more serious is afoot?
"I think you should start worrying ... anytime there's enough of a change when you go, 'Oh my God they don't seem like themselves,'" said Dr. Charles Raison, a professor of psychiatry at the University of Arizona College of Medicine.
Raison says the timeline is key; parents should perk up if for two to three weeks their children are "unremittingly down," feeling hopeless and negative, if they start to withdraw from friends and activities, and if they experience dramatic changes in sleep...