Age of Onset
May strike at age 9 or younger, though during adolescence is more common.
When It's Nothing
Sometimes moody kids are just moody and sensitive ones are just sensitive. Sadness triggered by a particular situation is also unlikely to be depression, provided the child adjusts and moves on.
When It's Something
Symptoms in kids are the same as in adults: loss of appetite and energy, irritability, difficulty sleeping, feelings of worthlessness, inability to feel enjoyment. Thoughts of suicide are also a sign.
Treatment
Cognitive therapy can help kids reframe feelings and change perspectives. Drugs may be used as an adjunct to treatment, though they have been associated with suicidal thoughts. Depression itself, however, carries its own suicide risks, so the medication decision must be made carefully.