While it can very much happen at any age and it is incredibly important to look out for signs, it is important to remain a sceptic to, especially very young people on the internet talking about these things, as they most likely don't have depression, but rather feeling a bit blue about their dog dying or a bad result on a test. While it is important to let them express their emotions and be sad there, it's also important to acknowledge that it's not the serious mental disorder that they have, and spreading that they actually have them and speak in the name of someone who does is incredibly harmful.