Is depression common in children and teens?

Yes: http://www.childstats.gov/americaschildren/health4.asp http://www.Nimh.Nih.Gov/statistics/1mdd_child.Shtml. Sx might differ in children and adolescents. In younger children depression might manifest as somatic complaints (headaches, tummy aches, school- and separation anxiety). In adolesecents, it's more complicated, given their developmental stages (more behavioral acting out, irritability).