Films with the main character/central theme being about depression?

I saw a trailer for a new film with mel gibson about him going through depression and dealing with it... it did make me wonder that depression is the common cold of mental health illnesses so you would expect there to of been more films covering this issue, and if there has been maybe they havent been done very well, i am aware theres a film made out of the book "its kind of a funny story" which looks REALLY good and a bit quirky but other than that i cant think of any other films where depression is dealt with is the main issue of the main character and is primarily what the film is about