there and young people have had bipolar disorder and where a youngster may be budding into a schitzophrenia. and parents know best. they can develop an understanding of how their youngster is typically developing and if there's major changes. there's a campaign about becomes extremely agitated or withdrawn. those are things we would say are potentially of concern and that's when somebody would get a professional opinion. >> and do we know what causes depression in children? you would think at that point in their lives obviously there can be circumstances and atmospheric influences but childhood should be a happy time and it's difficult to look at and think of a child as being a depressed person. >> yeah, i mean, sure. it's hard to imagine that but the reality is that absolutely about 10% of kids will develop a depressive episode at some point before they reach the age of 18. one thing a lot of people will be fascinated by is the cdc something does called the youth risk behavior survey. this is arv nation. and they ask have you had thoughts about seriously considering suicide in the last 12