Steve Peterson points out you [rarely see clinical depression](http://towercoda.blogspot.com/2006/10/epidemic-you-dont-see-on-film.html) in movies and TV. Which is odd, considering it’s much more common in real life than, say, retrograde amnesia.
What makes clinical depression un-cinematic is that it’s a negative affect: it’s characterized by a lack of motivation, a lack of action. Great writing can only do so much when you have a protagonist who doesn’t want to protagonate.
[Shortbus](http://johnaugust.com/archives/2006/i-heart-shortbus) has a clinically depressed character who goes off his meds — a decision that is as frustrating in a movie as it is in real life. While the character explains himself fairly well, he’s kind of a drag to be around. Again, realistic, but not particularly cinematic.